Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12C—BEER; PREPARATION OF BEER BY FERMENTATION; PREPARATION OF MALT FOR MAKING BEER; PREPARATION OF HOPS FOR MAKING BEER
  • C12C1/00—Preparation of malt
  • C12C1/18—Preparation of malt extract or of special kinds of malt, e.g. caramel, black malt
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01H—NEW PLANTS OR NON-TRANSGENIC PROCESSES FOR OBTAINING THEM; PLANT REPRODUCTION BY TISSUE CULTURE TECHNIQUES
  • A01H1/00—Processes for modifying genotypes ; Plants characterised by associated natural traits
  • A01H1/10—Processes for modifying non-agronomic quality output traits, e.g. for industrial processing; Value added, non-agronomic traits
  • A01H1/101—Processes for modifying non-agronomic quality output traits, e.g. for industrial processing; Value added, non-agronomic traits involving biosynthetic or metabolic pathways, i.e. metabolic engineering, e.g. nicotine or caffeine
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01H—NEW PLANTS OR NON-TRANSGENIC PROCESSES FOR OBTAINING THEM; PLANT REPRODUCTION BY TISSUE CULTURE TECHNIQUES
  • A01H5/00—Angiosperms, i.e. flowering plants, characterised by their plant parts; Angiosperms characterised otherwise than by their botanic taxonomy
  • A01H5/10—Seeds
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01H—NEW PLANTS OR NON-TRANSGENIC PROCESSES FOR OBTAINING THEM; PLANT REPRODUCTION BY TISSUE CULTURE TECHNIQUES
  • A01H6/00—Angiosperms, i.e. flowering plants, characterised by their botanic taxonomy
  • A01H6/46—Gramineae or Poaceae, e.g. ryegrass, rice, wheat or maize
  • A01H6/4624—Hordeum vulgarus [barley]
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12C—BEER; PREPARATION OF BEER BY FERMENTATION; PREPARATION OF MALT FOR MAKING BEER; PREPARATION OF HOPS FOR MAKING BEER
  • C12C11/00—Fermentation processes for beer
  • C12C11/003—Fermentation of beerwort
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12C—BEER; PREPARATION OF BEER BY FERMENTATION; PREPARATION OF MALT FOR MAKING BEER; PREPARATION OF HOPS FOR MAKING BEER
  • C12C12/00—Processes specially adapted for making special kinds of beer
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12C—BEER; PREPARATION OF BEER BY FERMENTATION; PREPARATION OF MALT FOR MAKING BEER; PREPARATION OF HOPS FOR MAKING BEER
  • C12C5/00—Other raw materials for the preparation of beer
  • C12C5/004—Enzymes
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12C—BEER; PREPARATION OF BEER BY FERMENTATION; PREPARATION OF MALT FOR MAKING BEER; PREPARATION OF HOPS FOR MAKING BEER
  • C12C7/00—Preparation of wort
  • C12C7/04—Preparation or treatment of the mash
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12C—BEER; PREPARATION OF BEER BY FERMENTATION; PREPARATION OF MALT FOR MAKING BEER; PREPARATION OF HOPS FOR MAKING BEER
  • C12C7/00—Preparation of wort
  • C12C7/04—Preparation or treatment of the mash
  • C12C7/047—Preparation or treatment of the mash part of the mash being unmalted cereal mash
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
  • C12N15/09—Recombinant DNA-technology
  • C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
  • C12N15/79—Vectors or expression systems specially adapted for eukaryotic hosts
  • C12N15/82—Vectors or expression systems specially adapted for eukaryotic hosts for plant cells, e.g. plant artificial chromosomes (PACs)
  • C12N15/8241—Phenotypically and genetically modified plants via recombinant DNA technology
  • C12N15/8242—Phenotypically and genetically modified plants via recombinant DNA technology with non-agronomic quality (output) traits, e.g. for industrial processing; Value added, non-agronomic traits
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
  • C12N15/09—Recombinant DNA-technology
  • C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
  • C12N15/79—Vectors or expression systems specially adapted for eukaryotic hosts
  • C12N15/82—Vectors or expression systems specially adapted for eukaryotic hosts for plant cells, e.g. plant artificial chromosomes (PACs)
  • C12N15/8241—Phenotypically and genetically modified plants via recombinant DNA technology
  • C12N15/8242—Phenotypically and genetically modified plants via recombinant DNA technology with non-agronomic quality (output) traits, e.g. for industrial processing; Value added, non-agronomic traits
  • C12N15/8243—Phenotypically and genetically modified plants via recombinant DNA technology with non-agronomic quality (output) traits, e.g. for industrial processing; Value added, non-agronomic traits involving biosynthetic or metabolic pathways, i.e. metabolic engineering, e.g. nicotine, caffeine
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
  • C12N9/0004—Oxidoreductases (1.)
  • C12N9/0069—Oxidoreductases (1.) acting on single donors with incorporation of molecular oxygen, i.e. oxygenases (1.13)

Definitions

• the present invention relates to plant biotechnology, disclosing barley and malt defective in synthesis of the lipoxygenase (LOX) enzyme LOX-1 , thus providing a new raw material for industrial usage.
• said raw material can be used for manufacturing a new and distinctive flavor-stable beer having no or negligible quantities of the off-flavor compound trans-2-nonenal (T2N).
• T2N is formed by the sequential action of LOX pathway enzymes, where the LOX-1 represents the primary activity, conferring dioxygenation of linoleic acid to yield 9-hydroperoxy octadecadienoic acid (9-HPODE).
• Barley and plant products of the invention exhibit no or only negligible quantities of 9-HPODE.
• the invention relates to beverages produced using said barley and/or malt.
• NaN 3 -derived mutagenesis has been used to induce genetic changes in barley to generate mutants blocked in the synthesis of anthocyanins and proanthocyanidins (von Wettstein et al., 1977; von Wettstein et al., 1985; Jende- Strid, 1991 ; Jende-Strid, 1993; Olsen et al., 1993).
• a second example relates to barley kernels mutagenized with NaN 3 to screen for high levels of free phosphate with the aim to identify low-phytate mutants (Rasmussen and Hatzak, 1998); a total of 10 mutants out of 2,000 screened kernels were identified.
• an early identification of DNA mutations for example to cancel further breeding with lines characterized by promoter mutations in the gene of intererest or where other DNA mutations influence expression - simply because environmental or physiological factors could confer reversion of the trait induced by the mutagen. Accordingly, there is a demand for finding alternative ways of detecting mutations of interest early in the breeding program. This should make the entire breeding process faster and economically of higher interest, thus maximizing the amount of grain produced on the land.
• a major proportion of the barley produced comprises malting varieties, the kernels of which are converted to malt through processes of controlled steeping, germination, and drying of the barley.
• malt-derived beverages including, but not limited to, beer and whisky.
• milled malt is subjected to a mashing process comprising a step-wise increase in temperature of a malt-water suspension which confers partial, enzymatic degradation and extraction of, for example, the kernel polymers starch and ⁇ -glucan.
• the aqueous mash is boiled with hops to yield the wort.
• Said wort is subsequently fermented with yeast, giving the beer product which - upon maturation - is bottled.
• the wort can also be used for the production of non-fermented malt beverages.
• Palatability and flavor stability of a beverage is an important factor of relevance to the composition of barley and malt. This is because natural flavor molecules derived from said barley and malt - or generated by the action of enzymes extracted from said barley and malt - may confer undesirable taste characteristics to the final product (Drost et al., 1990). In this respect, formation of the volatile compound giving a cardboard-like flavor appears to be of particular biochemical as well as economic interest. In 1970, the molecule responsible for cardboard-like flavor was isolated and identified as T2N, a nine-carbon (C 9 ) alkenal (Jamieson and Gheluwe, 1970).
• LOX-2 catalyzes the conversion of linoleic acid to 13-HPODE which is further metabolized to hexanal (FIG. 1 B), a C 6 aldehyde with a taste threshold level of around 0.4 ppm (Meilgaard, supra).
• hexanal FIG. 1 B
• C 6 aldehyde with a taste threshold level of around 0.4 ppm
• LOX activity is the sole enzymatic source for the generation of linoleic acid hydroperoxide precursors of relevance for the formation of the T2N- specific off-flavors, or whether the process of fatty acid autooxidation contributes as well. It is notable that C ⁇ 8 hydroperoxides can be further converted by more than seven different families of plant and animal enzymes, with all reactions collectively called the LOX pathway (Feussner and Wasternack, 2002); this pathway is also referred to as the oxylipin pathway. Oxylipins, as their name implies, are oxygenated lipid-derived molecules, which result from the oxygenation of unsaturated fatty acids via the LOX reaction and also include any molecules derived from such oxygenated molecules.
• Barley kernels and barley plants having a LOX-1 protein characterized by reduced activity were disclosed in PCT application PCT/I B01/00207 published as WO 02/053721 A1 to Douma et al. However, said application does not teach the generation and analysis of barley kernels with inactive LOX-1 enzyme.
• Several examples on mutated plants that synthesize low levels of LOX are known. For example, three soybean lines were identified in the early 1980s, each deficient in one of the three LOX enzymes in mature soybean seed: (/) LOX-1.
• LOX-1 Although the molecular basis of the LOX-1 null mutation remains uncertain, it correlates with the absence of the corresponding mature mRNA (Hildebrandt and Hymowitz, 1982; Start et al., 1986); (ii) LOX-2. Transcripts for the mutated gene were detected, and a single base change was observed which replaces a histidine ligand to the active site iron, leading to enzyme instability (Davies and Nielsen, 1986; Wang et al., 1994); (iii) LOX-3. LOX-3 null mutants exhibited no detectable levels of the corresponding transcript, probably as a consequence of c/s-acting elements in the gene promoter (Kitamura et al., 1983; Wang et al., 1995).
• null-LOX-2 line was found to carry a defect leading to the absence of most LOX-2 protein (Forster et al., 1999). Since this line exhibited a great decrease in the amount of mRNA for LOX-2, it was suggested that the mutation caused a dramatic reduction in mRNA stability.
• immunoblot screening of extracts revealed the presence of two natural cultivars, Daw Dam and CI-115, each lacking one of three LOX enzymes (Ramezanzadeh et al., 1999).
• LOX-H1 depletion resulted in a marked reduction of volatile aliphatic C 6 aldehydes, compounds involved in plant defense responses and acting as either signaling molecules for wound-induced gene expression or as antimicrobial substances.
• transgenic potato plants depleted in the expression of a gene for a LOX enzyme exhibited abnormal tuber development (Kolomiets et al., 2001 ). However, specific oxylipins that accounted for the tuber phenotype were not identified.
• antisense-mediated depletion of potato LOX-H3 suppressed the inducible defense response of the plant, concominant with a higher tuber yield (Royo et al., 1999).
• LOXs are of interest due to their ability to induce formation of free radicals, which can then attack other constituents, such as vitamins, colors, phenolic, proteins etc. It is notable that some free radicals are thought to play a role in the autooxidation of free fatty acids. Some free-radical-generating substances may withstand thermal processing and thus remain sufficiently active in processed foods to initiate changes in quality during storage of the product. Antioxidants are widely used as LOX inhibitors, some of which also inhibit the autooxidation of LOX substrates. However, no LOX inhibitors useful as a flavor-improving additive for beverages have been identified.
• LOX enzymes are also related to issues outside the field of manufacturing beer, such as LOX-catalyzed generation of hydroperoxy fatty acids that inhibit mycotoxin formation in plants susceptible to fungal contamination, for example as disclosed in U.S. Patent No. 5,942,661 to Keller.
• LOX enzymes in plant defense and wounding responses remains less clear, the enzymes are induced upon wounding and pathogen challenge (Bell and Mullet, 1991 ; Bell and Mullet, 1993; Melan et al., 1993; Sarvitz and Siedow, 1996).
• LOX enzymes' role in wounding and plant defence could be to produce reactive fatty acid hydroperoxides against pathogens (Rogers et al., 1988).
• LOXs may be induced by stresses to produce signal molecules, such as methyl jasmonate (Bell et al., supra).
• 13-HPODE produced by the action of a LOX enzyme, acts as a substrate for hydroperoxide-converting enzymes to produce flavor-active aldehydes (Noordermeer et al., 2002; Husson and Belin, 2002).
• Similar processes are disclosed in numerous patents, e.g. U.S. Pat. No. 6,150,145 to Hausler et al. and U.S. Patent No. 6,274,358 to Holtz et al.
• LOX enzymes have been shown to contribute several beneficial effects to bread-making (Casey, 1997).
• U.S. Patent No. 6,355,862 B1 to Handa and Kausch discloses that fruit quality can be enhanced by inhibiting production of LOX, such as giving a longer shelf life to the product.
• the present invention discloses that beverages prepared from such plants will have very low levels of T2N.
• the present invention discloses that beverages prepared from such plants will have very low levels of 9,12,13-THOE.
• the present invention discloses methods for preparing barley plants with no or very little LOX-1 activity.
• the invention discloses null mutations in the gene for LOX-1.
• the prospective benefits of the invention include a total elimination of T2N from the corresponding branch of the LOX pathway, and the invention thus provides a superior way for controlling T2N levels in the barley kernel; and beer produced from these kernels exhibit exceptional taste stability after prolonged storage, even at elevated temperatures.
• the present invention also provides methods for early mutation detection, and hence the disadvantages of late mutant characterization have been solved by the present invention. This makes use of a new attractive procedure for generating improved malting barley cultivars, introducing the sequential use of phenotype characterization and DNA sequence determination of target genes in a mutant population at an early time point in the breeding process. Isolated plants can be further improved using a variety of plant breeding methods.
• the present invention solves the current problems, limitations and disadvantages related to the presence of active LOX-1 enzyme in barley.
• this invention provides a novel, efficient screening method that significantly reduces the time and labor for screening chemically mutagenized barley.
• the present invention includes novel null-LOX-1 barleys, for example useful in the production of flavor-stable beer.
• the theoretical background art for plant LOX mutants, as described above, is related to plants having reduced levels of LOX activity.
• the present invention overcomes the limitations and disadvantages related to low or residual LOX activity by providing ways to effectively generate null-LOX-1 barley plants. Specific differences include:
• plants of the present invention comprise essentially no LOX-1 activity, preferably the plants are true null-LOX-1 plants - i.e. the plants exhibit a total I ack-of-f unction of LOX-1 protein;
• the true null-LOX-1 trait described herein could be identified by screening for the presence of a nonsense mutation in the corresponding gene. Accordingly, barley plants homozygous for that trait would be completely blocked in the synthesis of active enzyme - irrespective of growth conditions or environmental effects.
• soybean LOX mutants of the background art where biotic or abiotic conditions could affect changes in the physiological state of cells to confer mRNA stabilization with subsequent translation of LOX;
• the present invention relates to lower levels of the taste- specific compound T2N in a beverage as well as to lower levels of 9,12,13-THOE in a beverage;
• the soybean and rice LOX mutants are affected in molecules of the LOX pathway downstream of 13-HPODE, while the null-LOX-1 trait relates to that branch of the LOX pathway which comprises molecules downstream of 9-HPODE;
• the soybean mutants comprise irradiation-induced mutations in genes for LOX, and Daw Dam and CI-115 represent selected naturally occurring cultivar
• barley plants, parts or fragments thereof comprising less than 5%, preferably less than 1% of the LOX-1 activity of a wild-type barley plant. It is a second objective of the invention to provide kernels from a barley plant comprising less than 5%, preferably less than 1% of the LOX-1 activity of a wild-type plant.
• a third objective of the present invention is to provide compositions comprising a barley plant, or parts or fragments thereof comprising less than 5%, preferably less than 1% of the LOX-1 activity of a wild-type barley plant.
• malt compositions comprising a processed barley plant comprising less than 5%, preferably less than 1% of the LOX-1 activity of a wild-type barley plant.
• Malt compositions may preferably be pure malt compositions.
• malt compositions may also be for example blends of barley and malt.
• beverages having stable organoleptic qualities wherein said beverages are manufactured using the barley plant of the invention or part thereof.
• said beverages are manufactured using the malt composition, such as a pure malt composition or a blend of barley and malt, described herein above.
• said beverages consist of beer.
• said beverage is beer.
• compositions such as food compositions, feed compositions, or fragrance raw material compositions that comprise the barley plant according to the invention or parts thereof.
• an objective of the present invention is to provide methods for reducing the levels of a protein in a barley plant of the invention, wherein said method includes transforming said plant with a nucleic acid sequence comprising, as operable linked components, a promoter expressable in barley plants or parts thereof, a DNA sequence, and a transcriptional termination region, wherein expression of said DNA sequence reduces the expression of a gene encoding said protein by antisense, or co-suppression or RNA interference.
• An additional objective of the present invention is to provide methods of preparing a barley plant comprising less than 5%, preferably less than 1 % of the LOX-1 activity of a wild-type barley plant comprising the steps of: (i) Determining the LOX-1 activity in wild-type barley kernels or parts thereof; and (ii) Mutagenizing barley plants and/or barley kernels and/or barley embryos, thereby obtaining generation M0 barley; and (iii) Breeding said mutagenized barley plants, kernels and/or embryos for at least 2 generations, thereby obtaining generation Mx barley plants, wherein x is an integer >2; and (iv) Obtaining kernels or parts thereof from said Mx barley plants; and (v) Determining the LOX-1 activity in said kernels or parts thereof; and (vi) Selecting plants wherein the LOX-1 activity of the mutagenized kernels or parts thereof is less than 5% than the LOX-1 activity of the wild-type kernels or part thereof
• a barley plant comprising less than 5% of the LOX-1 activity of a wild-type barley plant. Still further, it is an objective of the present invention to provide methods of producing a beverage having stable organoleptic qualities comprising the steps of: (i) Providing a malt composition according to the invention; (ii) Processing said malt composition into a beverage;
• the present invention is based on the unpredicted outcome of functional studies of barley mutant D112 (herein also referred to as "mutant D112" or “barley D112”), which revealed a total loss-of-function with respect to the major 9-HPODE-forming enzyme LOX-1. It was a surprising discovery to detect a 10%:90% distribution of 9-HPODE: 13-HPODE in biochemical assays designed to determine the product profile following LOX-catalyzed conversion of linoleic acid.
• the null-LOX-1 trait can be introduced into any other barley plant, such as established barley varieties, for example established malting barley varieties, thus allowing production of flavor-stable beverages with prolonged shelf lives. This may for example be accomplished by conventional breeding methods well known to the skilled person. This approach will not only be independent of the geographical region where mutant D112-derived barley is grown, but also independent of the location where mutant D112-derived beer is produced and sold to customers. Barley plants of mutant D112, or plants derived thereof, are potentially an important economical factor for farmers that grow the crop, and for breweries that use it as a raw material for beer production or production of other barley based beverages. Other applications that depend on raw materials without
• 9-HPODE/9-HPOTE-forming activities are also anticipated to benefit from the properties of barley mutant D112.
• barley mutant D112 there is provided several novel malting barley mutants, for example the barley mutant D112 or the barley mutant A618 (herein also referred to as "mutant A618" or “barley A618").
• the present invention is therefore related to the kernels of barley mutants D112 or A618, to the plants of barley D112 or A618 and to methods for producing a barley plant derived from crossing barley mutants D112 or A618 with itself or another barley line.
• the present invention comprises null-LOX-1 variants generated by mutagenesis or transformation of barley mutant D112 or A618.
• all plants produced using barley mutants D112 or A618 - or a derivative thereof - as a parent plant are within the scope of this invention.
• the invention provides regenerable cells for use in tissue culture of barley mutant plant D112 or A618.
• the tissue culture will preferably be used for regeneration of plants having the characteristics of the foregoing barley plants, including morphological and genetic characteristics.
• the regenerated cells in such tissue cultures will be embryos, protoplasts, meristematic cells, callus, pollen, anthers, etc.
• the present invention provides barley plants regenerated form the tissue cultures of the invention.
• the present invention comprises malt derived from null-LOX-1 barley kernels.
• the present invention also relates to wort compositions prepared from null-LOX-1 barley plants or parts thereof or from malt compositions prepared from such barley plants.
• the invention further comprises beverages, such as beer manufactured using either null-LOX-1 barley kernels of the present invention or malt derived from said kernels.
• the invention relates to a plant product produced from a null— LOX-1 barley plant or parts thereof. Said plant product may be any product resulting from processing of said barley plant or part thereof.
• said plant product is selected from the group consisting of malt, wort, fermented beverages such as beer, non-fermented beverages, food products such as barley meal and feed products. It is also an object of the present invention to provide null-LOX-1 barley kernels exhibiting such levels of disease resistance that are indistinguishable from wild-type barley plants or even have improved disease resistance. Still further, the invention comprises null-LOX-1 barley kernels and malt derived from said kernels, where both kernels and malt exhibit reduced levels of mycotoxins. Also, the present invention comprises null-LOX-1 barley varieties with enhanced disease resistance relative to wild-type plants.
• null-LOX-1 barley having reduced disease resistance relative to wild-type plants are disclosed, provided that other characteristics of said plants provide benefits that are more important than the property of reduced disease resistance.
• the present invention provides null-LOX-1 barley kernels useful for the production of LOX pathway-derived fragrances, including green note compounds.
• the present invention provides for transgenic plants of null-LOX-1 barley mutants D112 or A618, or plants derived thereof, where the introduced gene(s) confer such traits as herbicide resistance, insect resistance, resistance for bacterial, fungal, or viral diseases, enhanced nutritional quality, and industrial usage.
• the gene may be an endogenous barley gene or, alternatively, a transgene introduced through genetic engineering techniques.
• the present invention provides for methods of reducing LOX-1 activity by use of LOX-1 inhibitors.
• Plant products, or products derived from plants, including beverages and beer, obtained by said methods may have properties similar to products prepared from null-LOX-1 barley as raw material.
• a can mean one or more, depending on the context in which it is used.
• agronomic trait describes a phenotypic trait of a plant that contributes to the performance or economic value of said plant. Such traits include disease resistance, insect resistance, virus resistance, nematode resistance, drought tolerance, high salinity tolerance, yield, plant height, days to maturity, kernel grading (i.e. kernel size fractionation), kernel nitrogen content and the like.
• antisense nucleotide sequence is intended a sequence that is in inverse orientation to the normal coding 5'-to-3' orientation of that nucleotide sequence.
• the antisense DNA sequence When present in a plant cell, the antisense DNA sequence preferably prevents normal expression of the nucleotide sequence for the endogenous gene, and may disrupt production of the corresponding, native protein.
• barley in reference to the process of making beer, particularly when used to describe the malting process, means barley kernels. In all other cases, unless otherwise specified, “barley” means the barley plant (Hordeum vulgare, I.) including any varieties.
• disease resistance is intended that the plants avoid the disease symptoms that are the outcome of plant-pathogen interactions. In this way, pathogens are prevented from causing plant diseases and the associated disease symptoms, or alternatively, the disease symptoms. Alternatively, the disease symptoms caused by the pathogen are minimized or reduced.
• Cereal plant as defined in this publication is a member of the Graminae plant family cultivated primarily for their starch-containing seeds. Cereal plants include.but are not limited to barley (Hordeum), wheat (Triticum), rice (Oryza), maize (Zea), rye (Secale), oat (Avena), sorghum (Sorghum), and Triticale, a rye-wheat hybrid.
• encoding or “encoded,” in the context of a specified nucleic acid, is meant comprising the information for translation into the specified protein.
• a nucleic acid encoding a protein may comprise non-translated sequences (e.g.
• introns within translated regions of the nucleic acid, or may lack such intervening non-translated sequences (e.g. in cDNA).
• the information by which a protein is encoded is specified by the use of codons.
• expression in the context of nucleic acids is to be understood as the transcription and and accumulation of sense mRNA or antisense RNA derived from a nucleic acid fragment.
• Expression used in the context of proteins refers to translation of mRNA into a polypeptide.
• flavor molecules is intended aldehydes and/or alcohols that are produced and are constituents of odor and/or taste in plants. In particular, flavor molecules include certain volatile alcohols and aldehydes.
• flavor molecules which are volatile include but are not limited to hexanal, (3Z)-hexenal, (2E)-hexenal, (2£)-hexenol, (3Z)-nonenal, (2E)-nonenal.
• the invention can be used to modulate levels of flavor molecules in plants.
• the term "gene” means the segment of DNA involved in producing a polypeptide chain; it includes regions preceding and following the coding region (promoter and terminator).
• Eukaryotic genes are discontinuous with proteins encoded by them, consisting of exons interrupted by introns. After transcription into RNA, the introns are removed by splicing to generate a mature messenger RNA (mRNA).
• the "splice sites" between exons are typically determined by consensus sequences acting as splice signals for the splicing process, consisting of a deletion of the intron from the primary RNA transcript and a joining or fusion of the ends of the remaining RNA on either side of the excised intron. In some cases alternate or different patterns of splicing can generate different proteins from the same single stretch of DNA.
• a native gene may be referred to as an endogenous gene.
• Gene-silencing is a method to alter gene expression. It refers to RNA silencing, which is a post-transcriptional gene-silencing mechanism conserved among various organisms. The method includes post-transcriptional gene silencing (PTGS) and RNA interference (RNAi).
• PTGS is a gene-silencing phenomenon of endogenous and exogenous homologous genes. Although most examples on PTGS are on the effects caused by co-suppression constructs or expression of transgenes in antisense orientation, it has also been observed in plants of conventional breeding programs, e.g. the Lgc1 mutation in rice (Kusaba et al., 2003). This mutation was found to suppress glutelin expression via RNA silencing, possibly due to a 3.5-kbp deletion between two highly similar genes for glutelin that forms a tail-to-tail inverted repeat that might produce a double-stranded RNA molecule - and thus a potent inducer of RNA silencing.
• RNA interference A second form of RNA silencing is known as RNA interference (RNAi), where the basic premise is the ability of double-stranded RNA to specifically block expression of its homologous gene when injected or ingested into cells (Goenczy et al., 2000).
• heterologous in reference to a nucleic acid is a nucleic acid that originates from a foreign species, or, if from the same species, is substantially modified from its native form in composition and/or genomic locus by deliberate human intervention.
• the term “germination” as used herein means the beginning or resumption of growth by a barley kernel in various compositions, such as normal soil as found in nature.
• Germination can also take place in the soil of pots placed in growth chambers an the like, or for example take place on wet filter paper placed in standard laboratory Petri dishes. Germination is generally understood to include hydration of the kernels, swelling of the kernels and inducing growth of the embryo. Environmental factors affecting germination include moisture, temperature and oxygen level. Root and shoot development are observed. "Green notes” is a term describing volatile flavor and fragrance molecules present in numerous plants, and characterized in organoleptic terms as fresh green and grassy. These molecules are produced by the plant from the degradation of lipids and free fatty acids, such as linoleic acid and linolenic acid. As used herein, the term "isolated" means that the material is removed from its original environment.
• a naturally-occurring polynucleotide or polypeptide present in a living organism is not isolated, but the same polynucleotide or polypeptide, separated from some or all of the coexisting materials in the natural system, is isolated.
• Such polynucleotides could be part of a vector and/or such polynycleotides or polypeptides could be part of a composition, and still be isolated because such vector or composition is not part of its natural environment.
• the term "kernel” is defined to comprise the cereal caryopsis, also denoted internal seed, the lemma and palea. In most barley varieties the lemma and palea adhere to the caryopsis and are a part of the kernel following threshing.
• kernel maturation or “grain development” refers to the period starting with fertilization in which metabolizable reserves, e.g. sugars, oligosaccharides, starch, phenolics, amino acids, and proteins are deposited, with and without vacuole targeting, to various tissues in the kernel (grain), e.g.
• LOX-1 activity refers to the enzymatic activity of the barley LOX-1 enzyme.
• LOX-1 activity is the enzyme catalyzed dioxygenation of linoleic acid to 9-HPODE. Even though the LOX-1 enzyme is capable of catalyzing other reactions, for the purpose of determining the activity of LOX-1 according to the present invention only the 9- HPODE forming activity should be considered.
• low-LOX refers to the presence of one or several mutations in one or several endogenous genes, causing a partial loss-of-function of a specified LOX enzyme, preferably with respect to - but not restricted to - enzymatic activity.
• the barley plants disclosed in PCT application PCT/I B01/00207 published as WO 02/053721A1 to Douma et al. produce a mutated LOX-1 enzyme having 10% residual activity compared with the corresponding wild-type enzyme.
• Low-LOX with reference to a plant refers to a plant having partial loss-of-function of the specified LOX enzyme.
• “Malting” is a special form of germination of barley kernels taking place under controlled environmental conditions, including, but not limited to maltery steep tanks and germination boxes.
• malting begins to occur during and/or after the barley kernels have been steeped. The malting process may be stopped by drying of the barley kernels.
• a malt composition prepared from null-LOX-1 barley is understood to comprise null-LOX-1 malt, such as pure null-LOX-1 malt or any blend of malt comprising null-LOX-1 malt.
• “Mashing” is the incubation of milled malt in water. Mashing is preferably performed at a specific temperature and in a specific volume of water.
• the temperature and volume of water is of importance as this affects the rate of decrease of enzyme activity derived from the malt, and hence the amount of especially starch hydrolysis that can occur.
• Mashing can occur in the presence of adjuncts, which is understood to comprise any carbohydrate source other than malt, e.g. barley (including null-LOX-1 barley), maize or rice adjunct, used principally as an additional source of extract.
• adjuncts which is understood to comprise any carbohydrate source other than malt, e.g. barley (including null-LOX-1 barley), maize or rice adjunct, used principally as an additional source of extract.
• the requirements for processing of the adjunct in the brewery depend on the state and type of adjunct used and in particular the starch gelatinization or liquefaction temperatures. If the gelatinization temperature is above the normal malt saccharification temperature, then the starch is gelatinized and liquefied before adding to the mash.
• “Mutations” include deletions, insertions, transversions and point mutations in the coding and noncoding regions of a gene. Deletions may be of the entire gene or of only a portion of the gene. Point mutations may result in stop codons, frameshift mutations or amino acid substitutions. Somatic mutations are those which occur only in certains cells or tissues of the plant and are not inherited to the next generation. Germline mutations can be found in any cell of the plant and are inherited.
• the term “null-LOX” refers to the presence of a mutation in a LOX-encoding gene, causing a total loss-of-function of the encoded LOX enzyme. Mutations that generate premature termination (nonsense) codons in a gene encoding LOX represent only one mechanism by which total loss-of-function can be obtained.
• nucleic acid fragments with reference to a plant refers to a plant having a total loss-of-function of the specified LOX enzyme.
• operably linked is a term used to refer to the association of two or more nucleic acid fragments on a single polynucleotide so that the function of one is affected by the other.
• a promoter is operably linked with a coding sequence when it is capable of affecting the expression of that coding sequence, i.e. that the coding sequence is under the transcriptional control of the promoter.
• Coding sequences can be operably linked to regulatory sequences in sense or antisense orientation.
• PCR or “polymerase chain reaction” is well known by those skilled in the art as a technique used for the amplification of specific DNA segments (U.S. Pat. Nos. 4,683,195 and 4,800,159 to Mullis et al.).
• Plant or “plant material” includes plant cells, plant protoplasts, plant cell tissue cultures from which barley plants can be regenerated, plant calli, and plant cells that are intact in plants or parts of plants, such as embryos, pollen, ovules, flowers, kernels, leaves, roots, root tips, anthers, or any part or product of a plant.
• plant product a product resulting from the processing of a plant or plant portion.
• Said plant product may thus for example be malt, wort, a fermented or non-fermented beverage, a food or a feed product.
• "recombinant” in reference to a protein is a protein that originates from a foreign species, or, if from the same species, is substantially modified from its native form in composition by deliberate human intervention.
• "RNA transcript” refers to the product resulting from RNA polymerase-catalyzed transcription of a DNA sequence. When the RNA transcript is a perfect complementary copy of the DNA sequence, it is referred to as the primary transcript.
• RNA sequence When an RNA sequence is derived from post-translational processing of the primary transcript, it is referred to as the mature RNA.
• Messenger RNA or “mRNA” refers to the RNA that is without introns and that can be translated into proteins by the cell.
• cDNA refers to DNA that is complementary to and derived from an mRNA template. The cDNA can be single-stranded or converted to a double-stranded form using, for example, the Klenow fragment of DNA polymerase I.
• Sense RNA refers to an RNA transcript that includes the mRNA and so can be translated into a polypeptide by the cell.
• Antisense RNA refers to an RNA transcript that is complementary to all or part of a target primary transcript or mRNA and that blocks the expression of a target gene.
• the complementarity of an antisense RNA may be with any part of the specific nucleotide sequence, i.e. at the 5' non-coding sequence, 3' non-coding sequence, introns, or the protein coding sequence.
• T2N means the free form of T2N.
• T2N potential is described the chemical substances which have the capacity to release T2N, or be converted into T2N, in one or more reactions.
• the T2N potential can be measured as the concentration of T2N in a solution, e.g. in wort or beer, following an incubation (e.g. for 2 h) at an elevated temperature (e.g. 100°C) and low acidity (e.g. pH 4.0).
• T2N adducts a term used to describe T2N conjugated to one or more substances, including, but not limited to, protein(s), sulfite, cellular debris, cell walls, or the like.
• T2N adducts per se are not sensed by humans as off-flavors.
• T2N released from said T2N adducts, for example by heat or acid, may give rise to an off-flavor.
• tissue culture indicates a composition comprising isolated cells of the same or a different type or a collection of such cells organized into parts of a plant, for example protoplasts, calli, embryos, pollen, anthers, and the like.
• Transformation means introducing DNA into an organism so that the DNA is maintained, either as an extrachromosomal element (without integration and stable inheritance) or chromosomal integrant (genetically stable inheritance).
• the method used herein for transformation of £. coli was the CaCI 2 -method (Sambrook and Russel, supra).
• For transformation of barley /Agrobacter/ ' -v -mediated transformation may be performed basically as described by Tingay et al. (1997) and Wang et al.
• transgenic is a gene that has been introduced into the genome by a transformation procedure.
• transgenic includes reference to a cell that has been modified by the introduction of a heterologous nucleic acid or that the cell is derived from a cell so modified.
• transgenic cells express genes that are not found in an identical form within the native form of the cell, or express native genes that are otherwise abnormally expressed, underexpressed, or not expressed at all as a result of deliberate human intervention.
• the term "transgenic” in reference to plants, particularly barley plants, as used herein does not encompass the alteration of the cell by methods of traditional plant breeding, e.g.
• wild-type barley plant refers to a conventional barley plant, preferably the term refers to the barley plant, from which the barley plants of the invention have been derived, i.e. the parent plants.
• wild-type barley plant is selected from the group consisting of cv.s Celeste, Lux, Prestige, Saloon, and Neruda. More preferably, the "wild-type barley plant” is cultivar Barke. Wild type barley cultivars or seeds thereof are generally available for example from common seed companies. 4. BRIEF DESCRIPTION OF THE SEQUENCE LISTING
• Sequence Listing contains the one letter code for nucleotide and amino acid sequence characters as defined in conformity with the standardized recommendations (Cornish-Bowden, 1985; IUPAC-IUB Joint Commission on Biochemical Nomenclature, 1984), which are herein incorporated by reference.
• the symbols and format used for nucleotide and amino acid sequence data comply with the rules governing sequence disclosures in patent applications.
• FIG. 1 is divided into three flow diagrams A, B and C.
• FIG. 1 A shows how
• NaN 3 -mutagenized barley kernels may be propagated. Kernels of generation MO grow into plants that develop kernels of generation M1. These may be sown and develop into M1 plants which produce new kernels of generation M2. Next, M2 plants grow and set kernels of generation M3, which may be harvested and used for screening analyses. M3 seeds may also be sown, and flowers of the corresponding plants used for crossings to obtain plants of generation M4.
• FIG. 1 B is a simplified representation how the biochemical LOX pathway operates to degrade linoleic acid, eventually yielding T2N.
• FIG. 1 C illustrates how linoleic acid may be transformed into the corresponding 9-hydroperoxy acid (9-HPODE) by the action of LOX-1 , followed by further enzymatic conversions by epoxy alcohol synthase and epoxide hydrolase into 9,12,13-trihydroxy-10-octadecenoic acid (9,12,13-THOE).
• FIG. 2 is a graphic comparison of total LOX activities measured in embryo extracts of cv. Barke, mutant D112, and in a control sample comprising heat-inactivated extract of cv. Barke embryos.
• FIG. 3 displays a graphic comparison of total LOX activities measured in embryo extracts of mutant A618, cv. Neruda, and in a control sample comprising heat- inactivated extract of cv. Barke embryos.
• FIG. 4 shows a comparison of total LOX activities measured in kernels of 12 individual M4 progeny lines of mutant D112. The activities of control samples consisting of kernel extracts of cv. Barke, and heat-inactivated kernel extracts of cv. Barke are included in the comparison.
• FIG. 5 summarizes the results of analyses for total LOX activity in 90 individual kernel extracts of M5 progeny lines of mutant D112. The activities of control kernel extracts of cv. Barke, and heat-inactivated kernel extracts of cv. Barke are included in the comparison.
• FIG. 6 gives a summary of a comparison of total LOX activities measured in 40 individual kernel extracts of M4 progeny lines of mutant A618. The activities of control samples with kernel extracts of cv. Barke and heat-inactivated kernel extracts of cv. Barke are included in the comparison.
• FIG. 7 consists of two separate immunoblots, showing that immunoreactive LOX-1 protein is not detectable in kernel extracts of mutant D112, generation M3.
• Each immunoblot was probed with an antibody to barley LOX-1 , and the samples consisted of extracts of E. coli cells expressing recombinant LOX-1 (lane 1 ), kernel extracts of cv. Vintage (lane 2), mutant line G (lane 3 and lane 7), cv. Barke (lane 6 and lane 8), and separate lines of mutant D112, generation M3 (lanes 4-5 and 9-16). The position of an immunoreactive LOX-1 protein is indicated.
• FIG. 8 shows two separate immunoblots, detailing the absence of LOX-1 in kernel extracts of mutant A618, generations M3 and M4. Each immunoblot was probed with an antibody to barley LOX-1 , and the samples consisted of kernel extracts of mutant line G (lane 1 ), cv. Neruda (lane 6 and lane 16). Extracts of randomly chosen M3 and M4 kernels that have not been through the LOX selection procedure were separated in lanes 2-5 and 8-12, respectively; all of these extracts contained a LOX-1 immunoreactive protein. The null-LOX-1 phenotype of a kernel extract of mutant A618, generation M3 (lane 7), was inherited in separate M4-progeny lines of mutant A618-82 (lanes 8-12). The position of an immunoreactive LOX-1 protein is indicated.
• FIG. 9 schematically illustrates the genetics of the backcrossing program for mutant D112 to cv. Prestige.
• the wild-type LOX-1 trait is assigned NN, while the null-LOX-1 mutant trait is nn. Plants having the genotypes underlined are subjected to crossings.
• FIG. 10 provides an illustration of seven separate immunoblots, each probed with an antibody to barley LOX-1.
• the immunoblots show the presence or absence of the immunoreactive LOX-1 protein in kernels of separate plants of the first backcross generation of mutant D112 to cv. Prestige (lanes 1 -6 and lanes 9-14), and the presence or absence of the immunoreactive LOX-1 protein in kernels of the second backcross generation of mutant D112 to cv. Prestige (lanes 17-22, lanes 25-30, lanes 33-38, lanes 41-45, and lanes 48-52).
• Control kernel extracts of mutant D112, lacking immunoreactive LOX-1 (lanes 7, 15, 23, 31 , 39, 46, 53), and cv. Prestige, containing immunoreactive LOX-1 (lanes 8, 16, 24, 32, 40, 47, 54), were used as controls.
• the position of an immunoreactive LOX-1 protein is indicated.
• FIG. 11 is a simplified, schematic overview of the beer production process without the use of adjuncts, but including steeping of the barley grain (1), malting (2), kiln drying (3), milling of the dried malt (4), mashing (5), filtration (6), wort boiling in the presence of added hops (7), fermentation in the presence of yeast (8), beer maturation (9), beer filtration (10), packaging, including -but not limited to - packaging into bottles, cans and the like (11), and labeling (12).
• the individual processes can be grouped into sections comprising malt production (1-3), wort production (4-7), fermentation (8-9), and preparation of the finished beer (10-12).
• FIG. 12 focuses on characteristics of beers produced using malt derived from barley of null-LOX-1 mutant D112.
• FIG. 12A illustrates the accumulation of free T2N during forced-aging for 4 weeks at 37°C.
• the aldehyde was measured in beer produced from malt of null-LOX-1 mutant D112 (A), and control malt of cv. Barke ( • ).
• the taste threshold level for T2N in beer is approximately 0.05 ppb.
• FIG. 12B provides a graphical representation of data compiled following the beer taste panel's evaluation on the individual taste characteristics of beers incubated at 20°C for 12 months.
• the beers were made of malt derived from either barley of cv. Barke (solid bars) or from barley of null-LOX-1 mutant D112 (open bars).
• FIG. 13 displays the chromatograms of HPLC analyses used to assay for the formation of 9- and 13-HPODEs in barley tissues.
• the levels of HPODEs were analyzed by measuring the absorbance at 234 nm, with the results given in milli absorbance units (mAU). Peaks of the elution profiles that correspond to 9-HPODE and 13-HPODE are indicated by arrows.
• FIG. 13A shows the chromatogram of 9-HPODE and 13-HPODE standards.
• FIG. 13B is a chromatogram of HPODEs formed in extracts prepared from mature embryos of cv. Barke.
• FIG. 13C is a chromatogram of HPODEs formed in extracts prepared from mature embryos of low-LOX kernels.
• FIG. 13D is a chromatogram of HPODEs formed in extracts of mature embryos of the null-LOX-1 mutant D112.
• FIG. 14 depicts the chromatograms of HPLC analyses used to assay for the formation of 9- and 13-HPODEs in malt.
• the levels of said HPODEs were analyzed by measuring the absorbance at 234 nm, with the results given in milli absorbance units (mAU). Peaks of the elution profiles that correspond to 9-HPODE and 13- HPODE are indicated by arrows.
• FIG. 14A shows the chromatogram of 9-HPODE and 13-HPODE standards. Chromatogram peaks corresponding to 9-HPODE and 13-HPODE are indicated by arrows.
• FIG. 14B is a chromatogram of HPODEs formed in extracts of malt from cv. Barke.
• FIG. 14C is a chromatogram of HPODEs formed in extracts of malt from low-LOX barley.
• FIG. 14D is a chromatogram of HPODEs formed in extracts of malt from the null-LOX-1 mutant D1
• FIG. 15 is a map showing the organization of the gene for barley LOX-1, spanning the start codon (ATG) and stop codon (TAA).
• the schematic drawing of the 4,165-bp-long sequence shows 7 exons (filled boxes) and 6 introns (lines).
• the position of the mutations identified in the gene for LOX-1 - i.e. specific for mutant line G (low-LOX), mutant A618 and mutant D112 - are indicated by arrows.
• FIG. 16 summarizes the predicted molecular differences related to the gene for LOX-1 of wild-type, mutant A618 and mutant D112 barley plants. The information listed in the columns marked “Result,” “Length in amino acids,” and “Mass in kDa” is predicted from the DNA sequence.
• FIG. 17 provides ways used to perform RT-PCR mutant analysis and transcript verification related to the barley gene encoding LOX-1.
• A is shematically shown the principle for RT-PCR detection of a specific transcript for the gene encoding LOX-1 in developing embryos of cv. Vintage and low-LOX-1 mutant line G.
• Primers consisted of FL821 [SEQ ID NO: 11] and FL852 [SEQ ID NO: 12], which anneal in the exons flanking the 83-bp-long intron 5; PCR product differences using either genomic DNA or mRNA templates are indicated.
• Lanes 1 and 5 contained marker fragments
• lanes 2, 3, and 4 contained the PCR products derived from embryo tissues of cv. Vintage after 20, 40, and 60 days after flowering (DAF), respectively.
• Lanes 6, 7 and 8 contain the products derived from embryo tissues of mutant line G after 20, 40, and 60 DAF, respectively.
• lanes 1-5 show the result of an experiment similar to that detailed for lanes 1-5 in B, while lanes 6, 7 and 8 contained the products derived from RT-PCR detection of a mutant D112 embryo-specific transcript of the gene for LOX-1 after 20, 40, and 60 DAF, respectively.
• D is shown an electropherogram that resulted from a sequencing reaction of a RT-PCR fragment specific for the gene for LOX-1. Sequence analysis revealed that the RT-PCR target RNA was free of DNA. The black triangle points to the splice point, indicating correct splicing of the transcript.
• FIG. 18 details the results of a SNP-assisted detection of barley mutant D112.
• the analysis was based on the generation of a specifc PCR fragment pattern using two sets of PCR reactions per sample, as schematically illustrated in A (primer set 1 consists of FL820 [SEQ ID NO: 13] and primer FL823 [SEQ ID NO: 15], and primer set 2 consists of FL820 [SEQ ID NO: 13] and FL825 [SEQ ID NO: 14]).
• A primer set 1 consists of FL820 [SEQ ID NO: 13] and primer FL823 [SEQ ID NO: 15]
• primer set 2 consists of FL820 [SEQ ID NO: 13] and FL825 [SEQ ID NO: 14]
• B is shown the result of a PCR pattern analysis of elite breeding material. Genomic DNA of plants were subjected to PCR analyses.
• results shown in lanes 2-3 (plant 1), 4-5 (plant 2), 6-7, (plant 3), 8-9 (plant 4), 10-11 (plant 5), 12-13 (plant 6), 14-15 (plant 7), 16-17 (plant 8), and 18-19 (plant 9) utilized primer combination 1 (even numbered lanes) or primer combination 2 (odd numbered lanes).
• Comparison of the banding pattern with that shown in A revealed that plants 1 , 2, 4, 5, 7, and 8 were homozygous mutants, while the genotype of plants 3, 6, and 9 could be classified as homozygous wild-type. Marker DNA was separated in lanes 1 and 20.
• FIG. 19 demonstrates the principle of multiplex SNP analysis of barley samples containing material of mutant G or mutant D112.
• the analysis utilized multiplex PCR reactions, such that the length of the fragment amplified could be related to the genotype of the material added. Amplification of a 370-bp fragment would indicate that a malt sample contained material derived from mutant line G, while the amplification of a 166-bp fragment would point to the presence of material derived from mutant D112.
• Panel A is a schematic illustration detailing how specific primer pairs, each with one primer that contains a sequence which is specific for the mutant of interest (asterisk; for mutant line G nucleotide number 2279 in the genomic clone for LOX-1 , and for mutant D112 position 3574).
• the primer combination FL918 [SEQ ID NO: 16] and FL920 [SEQ ID NO: 17] was used for detection of the mutant line G-specific mutation, while FL820 [SEQ ID NO: 13] and FL823 [SEQ ID NO: 15] were utilized for detection of the mutant D1 12-specific base change.
• B is shown how the relative quantities of mutant-specific material (lanes 2-7: mutant line G; lanes 8-13: mutant D112) in samples may enhance the synthesis of a specific PCR fragment (lanes 2 and 8: no mutant material added; lanes 3 and 9: 20% mutant material added; lanes 4 and 10: 40% mutant material added; lanes 5 and 11 : 60% mutant material added; lanes 6 and 12: 80% mutant material added; lanes 7 and 13: 100% mutant material). Lane 1 consisted of marker fragments.
• FIG. 20 presents the result of SDS-PAGE of affinity-purified, His-tagged LOX-1 from E. coli cells transformed with the vector plasmid pET19b (lanes 2-5), expression plasmid pETL1 (lanes 6-10), and expression plasmid pETL2 (lanes 11-15). Proteins from fractions comprising unbound proteins (lanes 2, 6, 11 ); first wash (lanes 3, 7, 12); second wash (lanes 4, 8, 13); first eluate (lanes 5, 9, 14); and second eluate (lanes 10 and 15) were analyzed.
• FIG. 21 illustrates plasmid inserts for transformation of barley.
• A is illustrated an expression cassette consisting of the maize ubiquitin-1 promoter and intron 1 (collectively denoted the UBI promoter), directing constitutive expression of the bar gene (BAR), which encodes the selectable marker phosphinothricin acetyl transferase. Transcription termination is provided by the NOS terminator sequence (N).
• B is illustrated an expression cassette consisting of the aforementioned UBI promoter, here directing constitutive expression of the barley cDNA sequence for LOX-1 in sense or antisense oritentation.
• C is illustrated an expression cassette consisting of the UBI promoter directing constitutive expression of a intron- containing hairpin construct, where the sequence of intron 1 of the Arabidopsis gene for fatty acid desaturase FAD2 intron 1 (Int), flanked by the sense arm (-») and antisense arm ( ⁇ -) of an approximately 200-bp-long fragment of the gene for LOX-1. Transcription termination is provided by the NOS terminator sequence (N).
• plasmid mixtures are used that comprise equal amounts of expression plasmids comprising the inserts detailed in A and B.
• mixtures are used that comprise equal amounts of expression plasmids comprising the inserts in A and C.
• FIG. 22 details experimental results concerning inhibitors that reduce LOX-1 activity.
• A is depicted the electrophoretic separation of proteins in a 10% SDS-PAGE, with separate lanes illustrating the result of a stepwise purification of His-tagged LOX-1 from E. coli cells (cf. Example 18).
• Proteins in crude extracts of transformants with vector pET19b and plasmid pETL1 are shown in lane 1 and lane 2, respectively, while lanes 3-5 contain separated proteins of wash solutions 2, 3 and 4.
• 3- ⁇ l sample aliquots from 1-ml eluates of the affinity column were separated in lane 6 (eluate 1 ), lane 7 (eluate 2), lane 8 (eluate 3), and lane 9 (eluate 4).
• the horizontal arrow indicates the position of recombinant LOX-1.
• Aliquots of LOX-1 from eluate 2 were used for the inhibitor studies, as summarized in B.
• the residual LOX-1 activity was measured following incubation with 5 ⁇ l of LOX-1 (eluate 2) in the presence of inhibitor, either NDGA (•) or octyl gallate (A).
• FIG. 23 provides a summary detailing levels of T2N in wort samples prepared from mashings without added inhibitor (open bars), or in the presence of 0.5 mM of the LOX-1 inhibitor octyl gallate (solid bars).
• Wild barley Hordeum vulgare ssp. spontaneum, is considered the progenitor of today's cultivated forms of barley. It has long been accepted that exploitation of this cereal provides a key to explaining the start of grain cultivation in the Fertile
• barley landraces Rare alleles and new mutational events were positively selected for by the farmers who quickly established the new traits in the domesticated plant populations, denoted “barley landraces.” These are genetically more closely related to modern cultivars than wild barley and represent a source of useful alleles for further breeding efforts (Ellis et al., 1998).
• barley landraces existed as highly heterogeneous mixtures of inbred lines and hybrid segregates, including few plants derived from random crossings in earlier generations. Most of the landraces have been displaced in advanced agricultures by pure line cultivars. Intermediate or high levels of genetic diversity characterize the remaining landraces. Initially, "modern barley" cultivars represented selections from landraces.
• the barley plant is a modern barley cultivar modified to comprise less that 1% of the LOX-1 activity of a corresponding wild type barley plant.
• the barley plant is not a barley landrace.
• the present invention relates to barley plants and parts thereof comprising less than 5%, preferably less than 4%, more preferably less than 3%, even more preferably less than 2%, yet more preferably less than 1 % of the LOX-1 activity of a wild-type barley plant.
• the barley plants of the invention comprising less than 1 % LOX-1 activity are herein also referred to as "null-LOX-1 barley plants.”
• the barley plant may be in any suitable form.
• the barley plant according to the invention may be a viable barley plant, a dried plant, a homogenized plant, such as milled barley kernels.
• the plant may be a mature plant, an embryo, a germinated kernel, a malted kernel or the like.
• Parts of barley plants may be any suitable part of the plant, such as kernels, embryos, leaves, stems, roots, flowers or fractions thereof. Fractions may for example be a section of a kernel, embryo, leaves, stem, root or flower. Parts of barley plants may also be a fraction of a homogenate or milled barley plant or kernel.
• parts of barley plants may be cells of said barley plant, preferably viable cells, that may be propagated in tissue cultures in vitro.
• null-LOX-1 barley plants comprise less than 5%, preferably less than 3%, more preferably less than 1%, preferably less than 0.5%, even more preferably less than 0.1 % of the activity of a wild-type barley plant.
• the activity may be determined by any suitable method, preferably however, the activity is determined using the method in Example 1 herein below.
• the null-LOX-1 barley plants have essentially no LOX-1 activity, more preferably no LOX-1 activity at all.
• Essentially no LOX-1 activity means no detectable LOX-1 activity using an assay for LOX-1 activity as described herein below.
• the almost absent LOX-1 activity of the null-LOX-1 barley may for example be the result of that said barley comprises a malfunctioning LOX-1 protein, such as a mutant LOX-1 protein.
• the null-LOX-1 barley comprises only very little or, more preferably, no LOX-1 protein, such as less than 5%, preferably less than 3%, more preferably less than 1%, preferably less than 0.5%, more preferably less than 0.1% LOX-1 protein compared to a wild-type barley plant.
• the null-LOX-1 barley comprises essentially no LOX-1 protein, most preferably no LOX- 1 protein at all.
• "Essentially no LOX-1 protein” is meant to cover no detectable LOX- 1 protein.
• the LOX-1 protein may be detected by any suitable means known to the person skilled in the art, however, preferably the protein is detected by techniques wherein LOX-1 protein is detected by specific antibodies to LOX-1. Said techniques may for example be Western blotting or ELISA.
• Said specific antibodies may be monoclonal or polyclonal, preferably however, said antibodies are polyclonal recognizing several different epitopes within the LOX-1 protein.
• LOX-1 protein may also be detected indirectly, for example by methods determining LOX-1 activity, by methods detecting mutations in the gene encoding LOX-1 or by methods detecting expression of the LOX-1 gene. Mutations in the gene encoding LOX-1 may for example be detected by sequencing said gene. Expression of the gene for LOX-1 may for example be detected by Nothern blotting or RT-PCR. In one preferred embodiment of the invention, LOX-1 protein is detected using the methods outlined in Example 4 of the instant publication. The term LOX-1 protein is meant to cover the full length LOX-1 protein of barley as set forth in [SEQ ID NO: 3] or [SEQ ID NO: 7] or a functional homologue thereof.
• null-LOX-1 barley preferably comprises a gene encoding a mutant form of LOX-1 lacking some or all of amino acids 520-862 of LOX-1. Said mutant LOX-1 may also lack other amino acid residues which are present in wild-type LOX-1. Accordingly, null-LOX-1 barley may comprise a truncated form of LOX-1 , which is not functional, such as an N-terminal or a C-terminal truncated form. Preferably, said truncated form comprises no more than 800, more preferably no more than
• said truncated form comprises only an N-terminal fragment of LOX-1.
• said truncated form comprises at the most the 800, more preferably at the most the 750, even more preferably at the most the 700, yet more preferably at the most the 690, even more preferably at the most the 680, yet more preferably at the most the 670, even more preferably at the most the 665 N-terminal amino acids of [SEQ ID NO: 3], such as no more than 665, for example no more than 650, such as no more than 600, for example at the most the 550, such as at the most the 500, for example at the most the 450, such as at the most the 425, for example at the most the 399 N-terminal amino acids of [SEQ ID NO: 3].
• the truncated form may consist of amino acid 1-665 of [SEQ ID NO: 3].
• the barley plant comprises a gene transcribed into mRNA encoding LOX-1 , wherein said mRNA comprises a nonsense codon or a stop codon upstream of the stop codon of wild-type LOX-1 mRNA.
• a nonsense codon is herein designated a premature nonsense codon.
• all genes transcribed into mRNA encoding LOX-1 of said plant comprise a premature non-sense codon or a stop codon.
• the non-sense codon or stop codon is preferably situated at the most 800, more preferably at the most the 750, even more preferably at the most the 700, yet more preferably at the most the 690, even more preferably at the most the 680, yet more preferably at the most the 670, even more preferably at the most the 665 codons down-stream of the start codon.
• the sequence of wild- type genomic DNA encoding LOX-1 is given in [SEQ ID NO: 1] or [SEQ ID NO: 5].
• the barley plant comprises a gene encoding LOX-1 , wherein pre-mRNA transcribed from said gene comprises the ribonucleic acid sequence corresponding to [SEQ ID NO: 2].
• the barley plant comprises a gene encoding mutant LOX-1 wherein said gene comprises at least one, such as 1, for example 2, such as 3, for example 4, such as 5 mutations in at least one, such as 1 , for example 2, such as 3 splice sites.
• said mutation(s) results in that said at least one splice site is non-functional.
• mRNA transcribed from such a gene will thus be abnormal due to aberrant splicing. Accordingly, it is preferred that mRNA transcribed from the LOX-1 gene of the null-LOX-1 barley plant according to the invention encodes no protein or a protein comprising only the N-terminus of LOX-1.
• Said protein may comprise other sequences encoded by the abnormal mRNA, which are not derived from the gene for LOX-1.
• the N- terminus of LOX-1 comprises amino acid 1 to amino acid N, wherein N is an integer in the range of 2 to 800, more preferably in the range of 2 to 750, yet more preferably in the range of 2 to 700, even more preferably in the range of 2 to 650, yet more preferably in the range of 2 to 600, even more preferably in the range of 2 to 550, yet more preferably in the range of 2 to 500, yet more preferably in the range of 2 to 450, even more preferably in the range of 2 to 400, yet more preferably in the range of 2 to 378.
• the barley plant comprises a gene encoding a mutant LOX-1 , wherein said gene has a mutation in a splice site leading to mRNA encoding a protein consisting of amino acids 1 to 378 of [SEQ ID NO: 3] as well as an additional amino acid sequence not derived from LOX-1.
• said mutant LOX-1 consists of the sequence as outlined in [SEQ ID NO: 8].
• the gene encoding mutant LOX-1 of the null-LOX-1 barley plant comprises a nonsense mutation, said mutation corresponding to a G ⁇ A substition at position 3574 of [SEQ ID NO: 1].
• the null-LOX-1 barley plant is a plant designated D112 having American Type Culture Collection (ATCC) deposit accession No. PTA-5487.
• the gene encoding LOX-1 of the null-LOX-1 barley plant comprises a non-functional intron 3 donor splice site.
• LOX-1 mRNA of said plant thus encodes a protein containing amino acids 1 -378 of LOX-1 and additional amino acids from intron 3, comprised in [SEQ ID NO: 8].
• the null-LOX-1 barley plant is a plant designated A618 having American Type Culture Collection (ATCC) deposit accession No PTA-5584.
• the barley plants according to the invention may also be the progeny of a null-LOX barley plant.
• the barley plant may be the progeny of the plant designated D1 12 having ATCC deposit accession No. PTA-5487 or the plant designated A618 having ATCC deposit accession No. PTA-5584.
• the barley plant according to the invention may be prepared by any suitable method known to the person skilled in the art, preferably by one of the methods outlined herein below (see for example Section 6.2 "Preparing null-LOX-1 barley").
• the null-LOX-1 barley plant according to the present invention has plant growth physiology and grain development comparable to wild-type barley.
• null-LOX-1 barley plant is similar to wild-type barley in respect of plant height, number of tillers per plant, onset of flowering and/or number of grains per spike. It is also an aspect of the invention to provide a null-LOX-1 barley plant, wherein said plant is characterized by: (i) having enhanced disease resistance; or (ii) having reduced potential for the production of mycotoxins; or (iii) comprising regenerable cells for use in tissue culture; or (iv) any combination of the traits of (i) to (iii).
• the barley plant is a null-LOX-1 barley plant with the proviso that said barley plant does not carry a mutation of the G in the splice donor site of intron 5.
• the invention also relates to plant products, such as malt, wort, fermented or non-fermented beverages, beer, food or feed products prepared from a null-LOX-1 barley plant or part thereof with the proviso that said barley plant does not carry a mutation of the G in the splice donor site of intron 5.
• Said G for example corresponds to the G at position 2968 of SEQ ID 1.
• Whether a plant product is prepared from a barley plant with a given mutation may be determined by isolating DNA from said plant product and identifying the presence or absence of said mutation by conventional methods known to the skilled person.
• DNA may for example be isolated from wort, beer or another beverage by freeze-drying, resuspension in an aqueous buffer, extraction with chloroform/isoamylalcohol, followed by alcohol precipitation.
• mutation of the G in the splice donor site of intron 5 may be identified in a similar manner as described in WO2004/085652 to Hirota et al.
• the barley plant according to the invention may be prepared by any suitable method known to the person skilled in the art.
• the barley plant of the invention is prepared by a method comprising the steps of mutagenizing barley plants or parts thereof, for example barley kernels, followed by screening and selecting barley plants for plants with less than 5% LOX-1 activity.
• the present invention in one aspect relates to a new and very efficient screening method, significantly superior to the screening method described in for example WO 02/053721 to Douma et al.
• the new screening method allows reproducibly to identify barley plants with no or very little LOX-1 activity.
• This new screening method includes obtaining kernels or parts thereof, such as embryos, from mutagenized barley and determining the LOX-1 activity in said kernels or parts thereof. Accordingly, it is an objective of the present invention to provide methods of preparing a barley plant comprising less than 5% of the LOX-1 activity of a wild-type barley plant comprising the steps of:
• Step (ii) in the above list may involve mutagenizing living material selected from the group consisting of barley plants, barley cells, barley tissue, barley kernels and barley embryos, preferably selected from the group consisting of barley plants, barley kernels and barley embryos, more preferably barley kernels.
• the LOX-1 activity of mutagenized kernels is determined using the same kind of material as that used for the determination of the LOX-1 activity of wild-type barley kernels, i.e it is preferred that the barley kernel or parts thereof of step (/) is the same kind of barley kernel or parts thereof as that mentioned in step (iv).
• step (iv) comprises determining LOX-1 activity in embryos of mutagenized barley plants. Mutagenesis may be performed by any suitable method.
• mutagenesis is performed by incubating a barley plant or a part thereof, for example barley kernels or individual cells from barley with a mutagenizing agent.
• Said agent is known to the person skilled in the art, for example, but not limited to sodium azide (NaN 3 ), ethyl methanesulfonate (EMS), azidoglycerol (AG, 3-azido-1,2-propanediol), methyl nitrosourea (MNU), and maleic hydrazide (MH).
• mutagenesis is performed by irradiating, for example by UV, a barley plant or a part thereof, such as the kernel.
• the mutagenesis is performed according to any of the methods outlined herein below in Section 6.4 "Chemical mutagenesis.”
• a non-limiting example of a suitable mutagenesis protocol is given in Example 1. It is preferred that the mutagenesis is performed in a manner such that the expected frequency of desired mutants is at least 0.5, such as in the range of 0.5 to 5, for example in the range of 0.9 to 2.3 per 10,000 grains, when screening M3 barley.
• mutagenesis is performed on barley kernels.
• the mutagenized kernels are designated generation M0 (see also FIG. 1A).
• barley plants, or parts thereof, that comprise less than 5%, preferably less than 1 % LOX-1 activity are selected. Selection may be performed according to any suitable method known to the person skilled in the art. Preferably, selection comprises obtaining a sample from a barley plant, such as from a barley kernel, determining the activity of LOX-1 in said sample and selecting plants, wherein said sample has less than 5%, or preferably less than 1 % of the LOX-1 activity of a wild-type barley plants. The sample may be taken from any suitable part of said plant.
• the sample is taken from the kernel, more preferably the sample is taken from the embryo tissue of a kernel, yet more preferably the sample consists of embryo tissue of a kernel.
• the sample must be homogenized using any suitable method prior to determining the LOX-1 activity.
• the sample is taken from generation Mx kernels, wherein x is an integer --2, preferably x is an integer in the range of 2 to 10, more preferably in the range of 3 to 8.
• LOX-1 activity is determined on M3 kernels or a sample derived from kernels. In that embodiment, it is preferred that mutagenised barley kernels (generation M0) are grown to obtain barley plants which are crossed to obtain kernels M1.
• Determination of LOX-1 activity may be carried out using any suitable assay, preferably by one of the methods outlined herein below.
• the assay monitors the dioxygenation of linoleic acid to 9-HPODE by LOX-1.
• assaying will therefore involve the steps of:
• Detection may be performed directly or indirectly. Any suitable detection method may be used with the present invention.
• linoleic acid hydroperoxides are detected. Linoleic acid hydroperoxides may for example be detected by coupling degradation of said linoleic acid hydroperoxides with an oxidative reaction, which develops a detectable compound. For example, this may be done as described in Example 1.
• 9-HPODE is detected directly, for example by spectrophotometric methods, such as HPLC as described in Example 9.
• LOX-1 activity is determined simply by determining the amount of 9-HPODE in a sample from a barley kernel.
• determination of LOX-1 activity is performed at a pH which allows high activity of LOX-1 , but only low activity of LOX-2.
• determination of LOX activity is preferably done at a pH in the range of 3 to 6.5, for example in the range of 3 to 4, such as in the range of 4 to 5, for example in the range of 5 to 6, such as in the range of 6 to 6.5.
• the pH is around 3, such as around 3.5, for example around 4, such as around 4.5, for example around 5, such as around 5.5, for example around 6, such as around 6.5, for example around 7.
• said sample is prepared at a suitable pH, such as at a pH in the range of 3 to 6.5, for example in the range of 3 to 4, such as in the range of 4 to 5, for example in the range of 5 to 6, such as in the range of 6 to 6.5.
• the pH is around 3, such as around 3.5, for example around 4, such as around 4.5, for example around 5, such as around 5.5, for example around 6, such as around 6.5, for example around 7.
• Preferred methods for selecting barley plants according to the invention are described herein below in the Section 6.5 "Selecting barley mutants.” A preferred example of a method for determination of LOX-1 activity is given in
• the selection procedure may be adapted for microtitre plate assay procedures, or other known repetitive, high-throughput assay formats that allow the rapid screening of many samples. It is preferred that at least 5,000, such as at least 7,500, for example at least 10,000, such as at least 15,000 mutagenized barley plants are analyzed for LOX-1 activity. Subsequent to the selection of useful barley plants with less than 5% LOX-1 activity, one or more additional screenings may optionally be performed. For example, selected mutants may be further propagated, and subsequent generations may be screened again for LOX-1 activity. Subsequent to selection of useful barley plants, these may be subjected to breeding, such as conventional breeding.
• the barley plant according to the invention may, however, also be prepared by other methods, for example by methods resulting in reduced transcription and/or translation of LOX-1.
• the null-LOX-1 barley plant may be prepared by transforming a barley plant with a nucleic acid sequence comprising, as operably linked components, a promoter expressable in barley plants, a DNA sequence, and a transcriptional termination region, wherein expression of said DNA sequence reduces the expression of the gene encoding LOX-1 by:
• the barley plant is prepared by a method involving transforming a barley plant with a nucleic acid sequence capable of reducing transcription or translation of a gene encoding LOX-1 , for example a nucleic acid sequence comprising antisense LOX-1 sequences.
• Said antisense sequences may, for example, be the antisense sequence of [SEQ ID NO: 1], or a fragment thereof.
• the antisense sequence should be operably linked to a promoter sequence from a gene expressed in barley plants.
• a non-limiting example of such a method is outlined in Example 16 herein below.
• the barley plant may be transformed by any useful method, for example
• null-LOX-1 barley plant is prepared by a method comprising the steps of: (i) Mutagenizing barley plants and/or barley kernels and/or barley embryos; and (ii) Determining the presence or absence of a mutation in the gene for LOX-1 , wherein said mutation leads to a gene for LOX-1 encoding a polypeptide form of LOX-1 comprising less than 700 contiguous amino acids of the sequence set forth in SEQ ID NO: 3, preferably said polypeptide is an N-terminal fragment of LOX-1 comprising at the most the 700 N-terminal amino acids of [SEQ ID NO: 3], (iii) Selecting plants carrying said mutation, thereby obtaining a barley plant comprising less than 5% of the LOX-1 activity of a wild-type barley plant.
• said mutation may lead to a gene for LOX-1 encoding any of the N-terminal LOX-1 fragments described herein above.
• Said mutation may be detected using any suitable method, for example sequencing the LOX-1 gene or single nucleotide polymorphism (SNP) analysis.
• SNP single nucleotide polymorphism
• One example of how to perform a SNP analysis is described in Example 13 and Example 14 herein below.
• the present invention also relates to compositions comprising the barley plants described above, or parts thereof, or compositions prepared from said barley plants, or parts thereof. Because said barley plants have less than 5%, preferably less than 1 % LOX-1 activity, compositions comprising, or prepared from, said barley plants, or parts thereof, will in general comprise very low levels of T2N and T2N potential. Examples of useful compositions comprising or prepared from null-LOX-1 barley are described herein below.
• compositions have: (i) Less than 30%, preferably less than 20%, more preferably less than 10%, even more preferably less than 5%, such as less than 2%, for example less than 1 % T2N; and/or (ii) Less than 30%, preferably less than 20%, more preferably less than 10%, even more preferably less than 5%, such as less than 2%, for example less than 1 % T2N potential;
• the present invention relates in one aspects to barley kernels comprising less than 1%) LOX-1 activity compared to wild-type kernels.
• the kernels comprise no LOX-1 activity.
• the present invention relates as well to compositions comprising said kernels and compositions prepared from said kernels.
• the invention relates to malt compositions prepared from null-LOX-1 kernels by malting.
• malting is to be understood germination of steeped barley kernels taking place under controlled environmental conditions (for example as illustrated in FIG. 11, steps 2 and 3). Malting is a process of controlled steeping and germination followed by drying of the barley grain.
• malt is for beverage production, it can also be utilized in other industrial processes, for example as an enzyme source in the baking industry, or as a flavoring and coloring agent in the food industry, for example as malt or as a malt flour, or indirectly as a malt syrup, etc.
• the present invention relates to methods of producing said malt composition. The methods preferably comprise the steps of:
• the malt may be produced by any of the methods described in Hoseney (1994). However, any other suitable method for producing malt may also be used with the present invention, such as methods for production of speciality malts, including, but limited to, methods of roasting the malt.
• any non-limiting example is described in Example 6.
• the invention relates to wort compositions prepared from malt compositions prepared from null-LOX-1 kernels.
• Said malt may be prepared from only null-LOX-1 kernels or mixtures comprises other kernels.
• the invention also relates to wort compositions prepared using null-LOX-1 barley or parts thereof, alone or mixed with other components.
• Said wort may be first and/or second and/or further wort.
• a wort composition will have a high content of amino nitrogen and fermentable carbohydrates, mainly maltose.
• steps 4 to 6 illustrate the common method for preparation of wort from malt.
• wort is prepared by incubating malt with water, i.e. by mashing. During mashing, the malt/water composition may be supplemented with additional carbohydrate-rich compositions, for example barley, maize or rice adjuncts.
• Unmalted cereal adjuncts usually contain no active enzymes, and therefore rely on malt or exogenous enzymes to provide enzymes necessary for sugar conversion.
• the first step in the wort production process is the milling of malt in order that water may gain access to grain particles in the mashing phase, which is fundamentally an extension of the malting process with enzymatic depolymerization of substrates.
• mashing milled malt is incubated with a liquid fraction such as water. The temperature is either kept constant (isothermal mashing) or gradually increased. In either case, soluble substances produced in malting and mashing are extracted into said liquid fraction before it is separated by filtration into wort and residual solid particles denoted spent grains.
• This wort may also be denoted first wort.
• a second wort is obtained.
• Further worts may be prepared by repeating the procedure.
• suitable procedures for preparation of wort is described in Hoseney (supra).
• the wort composition may also be prepared by incubating null-LOX-1 barley plants or parts thereof, such as unmalted null-LOX-1 plants or parts thereof with one or more suitable enzyme, such as enzyme compositions or enzyme mixture compositions, for example Ultraflo or Cereflo (Novozymes).
• the wort composition may also be prepared using a mixture of malt and unmalted barley plants or parts thereof, optionally adding one or more suitable enzymes during said preparation.
• the present invention also relates to food compositions, feed compositions, and fragrance raw material compositions that comprise null-LOX-1 barley plants or parts thereof.
• Food compositions may for example be, but are not limited to malted and unmalted barley kernels, barley meals, bread, porridge, cereal mixes comprising barley, health products, such as beverages comprising barley, barley syrups, and flaked, milled or extruded barley compositions.
• Feed compositions for example include compositions comprising barley kernels, and/or meals. Fragrance raw material compositions are described herein below.
• the invention also relates to mixtures of the compositions of the invention.
• the invention in one aspect relates to a composition prepared by a mixture of (i) a composition comprising a barley plant or a part thereof, comprising less than 5% of the LOX-1 activity of a wild-type barley plant plant, and (ii) a malt composition prepared from null-LOX-1 kernels.
• the present invention relates to beverages, more preferred malt-derived beverages, even more preferred alcoholic beverages, such as beer having stable organoleptic qualities, wherein said beverage is prepared using null-LOX-1 barley or parts thereof.
• the beverage is preferably prepared by fermentation of null-LOX-1 barley or parts thereof or extracts thereof, for example by fermentation of wort produced using malt produced from null-LOX-1 barley, alone or in combination with other ingredients.
• the beverage is a non- fermented beverage, for example wort.
• said beverage may be prepared from unmalted barley plants or parts thereof.
• said beverage is prepared from a malt composition prepared from null-LOX-1 barley kernels.
• said beverage is beer. This may be any kind of beer known to the person skilled in the art. In one embodiment the beer is for example a lager beer.
• the beer is preferably brewed using a malt composition comprising germinated null-LOX-1 barley.
• the malt composition may, however, also comprise other components, for example other germinated or ungerminated cereals, such as wild-type barley, null-LOX-1 barley, wheat and/or rye, or non-germinated raw materials comprising sugars or compositions derived from malted or unmalted raw materials, for example syrup compositions.
• "Organoleptic qualities" means qualities appealing to the olfactory and taste senses. These are analyzed, for example, by a trained taste panel. Preferably, said trained taste panel is trained specifically for recognition of aldehyde off-flavors, such as T2N.
• the taste panel will consist of in the range of 3 to 30 members, for example in the range of 5 to 15 members.
• the taste panel may evaluate the presence of various flavors, such as off-flavors, such papery, oxidized, aged and bready flavors.
• a method of determining the "organoleptic qualities" of a beverage is described in Example 6, herein below.
• the stable organoleptic qualities are at least partly a result of low production of T2N or T2N potential.
• a barley plant such as beer
• a barley plant such as beer
• a barley plant preferably comprising less than 50%, preferably less than 40%, more preferably less than 35%, such as less than 30%, for example less than 20%, such as less than 10%, for example preferably less than 5%, such as less than 2%, for example less than 1% T2N and/or T2N potential compared to a beverage prepared from wild-type barley after storage for at least 1 week, preferably at least 2 weeks, more preferably at least 3 weeks, even more preferably for at least 4 weeks, such as in the range of 1 to 3 months, for example in the range of 3 to 6 months, such as in the range of 6 to 12 months, for example for more than one year.
• the beverages of the invention preferably comprise at the most 0.07, preferably at the most 0.06, more preferably at the most 0.05, even more preferably at the most 0.04, such as at the most 0.03 ppb (parts per billion) free T2N after storage for at least 1 week, preferably at least 2 weeks, more preferably at least 3 weeks, even more preferably for at least 4 weeks, such as in the range of 1 to 3 months, for example in the range of 3 to 6 months, such as in the range of 6 to 12 months, for example for more than one year after storage at a temperature in the range of 15°C to 40°C, preferably in the range of 30°C to 37°C, more preferably at 37°C.
• the beverage also comprises in the range of 1 to 10 ppm (parts per million) sulfite, more preferably in the range of 2 to 8 ppm, more preferably in the range of 3 to 7 ppm, yet more preferably in the range of 4 to 6 ppm sulfite.
• the beverages according to the invention comprise at the most 0.04, more preferably at the most 0.03, for example at the most 0.025 ppb free T2N after storage for 2 weeks at 37°C.
• the beverages according to the invention comprise at the most 0.07, preferably at the most 0.06, more preferably at the most 0.05, even more preferably at the most 0.04, such as at the most 0.03 ppb (parts per billion) free T2N after storage for 4 weeks at 37°C in the presence of in the range of 4 to 6 ppm sulfite. It preferred that the beverages according to the present invention have a less papery taste compared to a similar beverage prepared from a different barley than null-LOX-1 barley after storage for at least 10 months at in the range of 15 to 25°C, such as around 20°C.
• said papery taste is less than 90%, more preferably less than 80%, such as less than 70% as evaluated by a trained taste panel.
• the invention relates to beverages, such as beer, with low levels of certain trihydroxyoctadecenoic acids, in particular to beverages with low levels of 9,12,13-THOE.
• Trihydroxyoctadecenoic acids have a bitter taste (Baur and Grosch, 1977 and Baur et al., 1977) and are therefore undesirable. It is thus desirable that the level of 9,12,13-THOE is as low as possible, preferably lower than 1.3 ppm, such as lower than 1 ppm.
• the overall concentration of 9,12,13-THOE in a malt-derived beverage is also dependent on the amount of malt used for preparation of said specific beverage.
• a strong beer will comprise more 9,12,13-THOE than a lighter beer and a higher over-all level of 9,12,13-THOE will be acceptable in a stronger beer.
• the beverage according to the invention comprises a lower level of 9,12,13-THOE than a normal beer of a similar kind.
• Such beverage may be obtained by using null-LOX-1 barley for preparation of said beverage.
• preferred beverages according to the invention comprises a low ratio of 9,12,13- THOE compared to an internal standard, which corrects for the amount of malt used in the preparation of said beverage.
• Said standard may for example be another trihydroxyoctadecenoic acid. It is thus important for the quality of a beverage, such as beer, that the ratio of various trihydroxyoctadecenoic acids (THAs) is kept within a specific range.
• T2N trihydroxyoctadecenoic acids
• beverages prepared from null-LOX-1 barley according to the invention also have a very low level of 9,12,13-THOE (see fig.
• the present invention relates to beverages, such as beer, having stable organoleptic qualities, wherein said beverage is manufactured using a barley plant or parts thereof, preferably null-LOX-1 barley and wherein the ratio of 9,12,13-THA to 9,10,13-THA within said beverage is at the most 1.8, preferably at the most 1.7, more preferably at the most 1.6, yet more preferably at the most 1.5, even more preferably at the most 1.4. It is thus very much preferred that said ratio is in the range of 0 to 1.8, preferably in the range of 0 to 1.6, such as in the range of 0 to 1.4.
• said ratio is approximately 1.3.
• the amount of 9,12,13-THOE and 9,10,13-THOE in a beverage may be determined by standard methods, for example by gas chromatography- mass spectrometry for example as described in Hamber, 1991.
• said THAs are oxylipins of linoleic acid conversion.
• beverages with such THA ratios may be prepared using the barley plant according the invention.
• said beverages are prepared using no other barley than null-LOX-1 barley, such as no other malt than malt prepared from null-LOX-1 barley.
• the beverage comprises:
• the invention relates to a beverage, such as beer with improved foam stability compared to a similar conventional beverage.
• beverages may for example be prepared from null-LOX-1 barley or parts thereof, for example malt.
• Foam stability may for example be determined as described in Brautechnische Analysenmetoden, 2002.
• the invention also relates to methods of producing said beverage. The methods preferably comprise the steps of:
• the beverage is beer.
• the processing step preferably comprises preparing wort from said malt composition, for example by any of the methods described herein above and fermenting said wort.
• alcoholic beverages such as beer may be manufactured from malted and/or unmalted barley grains. Malt, in addition to hops and yeast, contributes to flavor and color of the beer. Furthermore, malt functions as a source of fermentable sugar and enzymes.
• FIG. 11 A schematic representation of a general process of beer production is shown in FIG. 11 , while detailed descriptions of examples of suitable methods for malting and brewing can be found, for example, in a recent publication by Hoseney (supra).
• the malt composition for said beverage e.g. beer, malt drinks or non-fermented wort may for example be obtained by any of the methods described herein above.
• Wort may be prepared from said malt composition as described herein above.
• the first step of producing beer from wort preferably involves boiling said wort.
• wort During boiling other ingredients may be added, for example hops that provide the typical bitter and aromatic beer characteristics. Boiling of wort also causes aggregation between polyphenols and denatured proteins, which mainly precipitate during the subsequent phase of wort cooling.
• yeast Preferably said yeast is brewer's yeast, Saccharomyces carisbergensis.
• the wort will be fermented for any suitable time period, in general for in the range of 1 to 100 days.
• sugar is converted to alcohol and CO 2 concomitantly with the development of some flavor substances.
• the beer may be further processed. In general it will be chilled.
• the beer may also be filtered and/or lagered - a process that develops a pleasant aroma and a flavor less yeasty.
• the beer may be pasteurized or filtered, before it is packaged (e.g. bottled or canned).
• the present invention is based, at least in part, on the use of chemical mutagenesis of barley kernels, a method that is known to introduce mutations at random.
• Mutagenesis of barley may be performed using any mutagenizing chemical, however preferably it is performed by treating kernels with NaN 3 , letting the surviving kernels germinate, and then analyzing off-spring plants.
• the plant generation growing from the mutagenized kernels, referred to as MO contains heterozygote chimeras for any given mutation.
• Progeny collected after self-pollination are referred to as the M1 generation, and segregates both heterozygotes and homozygotes for a given mutation (cf. FIG. 1A and FIG. 9).
• Treating kernels with NaN 3 is not equivalent to treating a single cell, because the kernels after the treatment will contain some nonmutant cells and a variety of cells having DNA mutations. Since mutations in cell lineages that do not lead to the germ line will be lost, the goal is to target the mutagen to the few cells that develop into reproductive tissues which contribute to development of the M1 generation.
• albino chimeras and albino plants were counted in the M0 and M1 generation, respectively. Scoring mutant number as a function of surviving plants gives an estimate for the mutation efficiency, while scoring mutant number as a function of treated seeds measures the combination of both mutation efficiency and kernel kill.
• NMD nonsense-mediated mRNA decay
• One aspect of the present invention is to provide screening conditions for LOX-1 activity, wherein the activity from LOX-2 is diminished.
• the methods are based on the surprising discovery that the nature of barley tissue to be screened and the reaction conditions can enhance LOX activity derived from enzyme LOX-1 and diminish that from enzyme LOX-2. While the screening for low-LOX mutants as detailed in PCT application PCT/IB01/00207 published as WO 02/053721A1 to Douma et al. utilized a proteinaceous extract of barley leaf tips, with determination of enzymic activity at pH 7.5, the present publication details advantageous screening parameters allowing reproducibly to identify null-LOX barley mutants.
• tissue comprises the barley kernel, more preferably embryos of barley kernels.
• the screening will be performed on an extract of said tissue, i.e an extract of barley kernels or barley embryos. More preferably, extracts for LOX-1 activity determination comprise or most preferably consist of homogenized embryo tissue of dry barley kernels. In this way, only marginal activity derived from LOX-2 will contribute to the activity determinations.
• assays for LOX-1 activity are performed at a pH which preferably inactivates allene oxide synthase enzymes, thus affording HPODEs in good yield. 6.6 Plant breeding
• the objective is to provide agronomically useful barley plants comprising the null-LOX-1 trait.
• Crop development can be seen as an extended process that only begins with the introduction of the new trait. From the perspective of a plant breeder, this step almost always results in a plant that has a less desirable overall profile of agronomic traits than do current commercial varieties.
• null-LOX-1 trait there are other important factors to be considered in the art of generating a commercial malting barley variety, for example kernel yield, kernel size and other parameters that relate to malting performance.
• Another object of the present invention is to provide agronomically elite barley plants comprising the null-LOX-1 trait. Accordingly, this invention also is directed to methods for producing a new null-LOX-1 barley plant by crossing a first parent barley plant with a second parent barley plant, wherein the first or second plant is a null-LOX-1 barley. Additionally, both first and second parent barley plants can come from a null-LOX-1 barley variety. Thus, any such methods using the null-LOX-1 barley variety are part of this invention: selfing, backcrosses, crosses to populations, and the like.
• null-LOX-1 barley variety As a parent are within the scope of this invention, including those developed from varieties derived from a null-LOX-1 barley variety.
• the null-LOX-1 barley can also be used for genetic transformation in such cases where exogenous DNA is introduced and expressed in the null-LOX-1 plant or plant tissue.
• Backcrossing methods can be used with the present invention to introduce a null-LOX characteristic of a mutated barley plant into another variety, for example cv. Scarlett or cv. Jersey, both of which are contemporary, high-yielding malting barley cultivars.
• null-LOX-1 progeny from this cross are then crossed again to the recurrent parent, with the process being repeated until a barley plant is obtained wherein essentially all of the characteristics specified by the recurrent parent are recovered in the converted plant, in addition to the transferred genetic set-up for the null-LOX-1 trait of the nonrecurrent parent.
• the last backcross generation is then selfed to give pure breeding progeny for the null-LOX-1 trait (cf. FIG. 9).
• Having a suitable recurrent parent is important for a successful backcrossing procedure, the goal of which is to introduce the null-LOX-1 trait into the original variety.
• the genetic set-up of the recurrent variety is modified with that for the low-LOX-1 trait from the nonrecurrent parent, while retaining essentially all of the rest of that from the original variety.
• backcrossing methods are simplified when the characteristic being transferred is a dominant allele, it was possible to backcross that of the recessive null-LOX-1 trait - but in this case it was necessary to introduce a biochemical analysis to assess whether the desired characteristic was transferred.
• a way to accelerate the process of plant breeding comprises initial multiplication of generated mutants by application of tissue culture and regeneration techniques.
• another aspect of the present invention is to provide cells, which upon growth and differentiation produce barley plants having the null-LOX-1 trait.
• breeding may involve traditional crossings, preparing fertile anther-derived plants or using microspore culture.
• An important object of the present invention is to provide barley plants that lack the capacity to synthesize active LOX-1 enzyme.
• LOXs are large monomeric proteins with a single non-heme iron factor. Inspection of the Protein Data Bank at http://www.rcsb.org/pdb revealed that the structure of several LOX enzymes have been solved by X-ray crystallography. The proteins share an overall fold and domain organization, with each having a smaller N-terminal eight-stranded ⁇ -barrel domain and a larger C-terminal domain composed mostly of long ⁇ -helices.
• the iron atom is located at the C-terminal domain where it is coordinated to histidine residues and, uniquely, to the carboxyl terminus of the polypeptide, which happens to be an isoleucine.
• Several channels lead from the surface of the protein to the vicinity of the iron site, and these presumably afford access for the substrates, polyunsaturated fatty acids, and molecular oxygen, to the active site.
• the present invention relates to barley plants, or products thereof, blocked in the capacity to form the alkenal T2N.
• LOX enzymes catalyze dioxygenation of polyunsaturated fatty acids with a c/s-1,c.s-4 pentadiene system.
• the C 18 polyunsaturated fatty acids linoleic acid (18:2 ' ) and ⁇ 9 12 15 ⁇ -linolenic acid (18:3 ' ' ) are major LOX substrates.
• the lipoxygenase pathway of fatty acid metabolism is initiated by the addition of molecular oxygen at the C-9 or C-13 position of the acyl chain yielding the corresponding 9- and 13-linoleic or linolenic acid hydroperoxides.
• molecular oxygen at the C-9 or C-13 position of the acyl chain yielding the corresponding 9- and 13-linoleic or linolenic acid hydroperoxides.
• HPODEs 9- or 13-hydroperoxy octadecadienoic acids
• HPOTEs 9- or 13-hydroperoxy octadecatrienoic acids
• both 9- and 13-hydroperoxides can be subsequently cleaved to short-chain oxoacids and aldehydes (cf. FIG. 1 B). It is notable that 9-HPODE can be further metabolized to 9,12,13-THOE (cf. FIG. 1 C), a THOE having a bitter taste (Baur et al., 1977; Baur and Grosch, 1977). Accordingly, plants with LOX-1 inactivated will form THOEs in ratios different from that observed in wild type plants.
• the present invention encompasses influencing production of downstream metabolites of LOX-1 catalysis, which are produced not as a direct product of a LOX-1 -catalyzed reaction, but as a result of a subsequent reaction of a series of reactions, involving a product of LOX-1 catalysis. These reactions include spontaneous, factor-induced or enzyme-catalyzed isomerization.
• the production of these downstream metabolites could be influenced by modulating the expression of hydroperoxide lyase (HPL).
• HPL hydroperoxide lyase
• down-regulation of the genes encoding ⁇ 9-desaturase (converts stearic acid into oleic acid) or ⁇ 12-desaturase (converts oleic acid into linoleic acid) is expected to alter the relative proportions of the C ⁇ 8 fatty acids (stearic, oleic and linoleic acid) by decreasing the levels of the fatty acids downstream of the relevant enzyme and increasing the levels of the intermediate fatty acid substrate.
• oilseed crops examples include - but are not limited to - high-stearic (HS) soybean (Graef et al., 1985), high-oleic (HO) rapeseed (Auld et al., 1992), as well as HS and HO sunflower by Osorio et al. (1995) and Soldatov (1976), respectively.
• HS high-stearic
• HO high-oleic
• the invention encompasses production of aldehydes which are not direct products of LOX-1 action, but are produced by the action of enzymes of the LOX pathway, or by the isomerization of aldehydes, for example, isomerization of (3Z)-nonenal to (2£)-nonenal as provided in FIG. 1 B. It is also recognized that the invention encompasses production of such alcohols which correspond to the aldehydes produced by enzymes of the LOX pathway, and/or which correspond to aldehydes produced as a result of said isomerization.
• Said alcohols are typically produced by the action of enzyme members of the aldo-keto reductase superfamily (Srivastava et al., 1999), for example through enzymatic conversion of (2£)-nonenal to (2E)-nonenol.
• a further object of the present invention is to reduce or eliminate molecules related to the formation of T2N, including the formation of T2N precursors and aldehyde adducts.
• this aldehyde When this aldehyde is generated in the process of making beer at a production stage before fermentation, it can participate in the formation of adducts through binding to for example amino acids and proteins (Noel and Collin, 1995) - but possibly also nucleic acids, glutathione or the like - and subsequently be protected from reduction or oxidation by fermenting yeast (Lermusieau et al., 1999). However, T2N adducts can also be formed with sulfite during fermentation, rendering the aldehyde flavor-inactive (Nyborg et al., supra).
• T2N adducts are transferred to the finished beer, in which free T2N is liberated (Liegeois et al., 2002), the conditions of acidity and temperature being important factors in this process.
• T2N adducts comprise part of the T2N potential, a measure for the degradation of T2N adducts to free T2N under defined reaction conditions, e.g. incubation at 100°C, pH 4.0, for 2 h.
• the skilled artisan knows how to relate the T2N potential as an indicator of how beer will release T2N during storage, for example as described by Drost et al. (supra).
• Barley kernels of the instant invention are restricted in the LOX-1 -catalyzed formation of 9-HPODE, a molecule that normally functions as a precursor in the LOX pathway branch that yields T2N. Beers produced using null-LOX barley kernels will therefore not only possess a very low level of T2N, but also a very low level of T2N potential.
• null-LOX-1 barley kernels yielding beer products that totally lack T2N, or contain insignificant levels of T2N potential, including T2N adducts. Consequently, there is essentially no, or only insignificant, development of T2N-specific off-flavors during storage of beer produced using null-LOX-1 barley.
• the present invention further relates to disease resistant barley.
• Plant LOXs are considered to be involved in the development of active disease resistance mechanisms, collectivley known as the hypersensitive response (HR), a form of programmed cell death (Rusterucci et al., 1999).
• HR hypersensitive response
• a form of programmed cell death Rusterucci et al., 1999.
• HR hypersensitive response
• an infection event is followed by rapid cell death of plant cells localized around the infection site, and this leads to the formation of a necrotic lesion. In this way, pathogen spread is limited and prevents further damage to the remainder of the plant organ.
• HR is linked to expression of LOXs having specificity for the generation of 9-HPODE and 9-HPOTE (Rusterucci et al., supra; Jalloul et al., 2002), possibly because the massive production of hydroperoxy fatty acids confers tissue necrosis.
• the gene encoding LOX-1 is primarily expressed in barley kernels, while numerous additional LOX enzymes are expressed in the leaves of the plants. Accordingly, the LOX pathway branches leading to the formation of 9-HPODE, 13-HPODE, 9-HPOTE, and 13-HPODE are functional in barley leaves, and different sets of oxylipins reflect separate infection and wounding events.
• null-LOX-1 barley plants of the invention may prevent, reduce, ameliorate or eliminate the presence of a pathogen, a product of a pathogen, or a product of a plant-pathogen interaction.
• a pathogen is Aspergillus (see herein below).
• the invention relates to a null-LOX-1 barley plant exhibiting enhanced disease resistance.
• the present invention also discloses the use of barley plants with reduced susceptibility to Aspergillus colonization.
• Aspergillus is a troublesome colonizer of barley kernels, often causing contamination with the carcinogenic mycotoxins aflatoxin and sterigmatocystin. Since the production of aflatoxin by the fungus is influenced by high levels of 9-HPODE, 9-HPOTE, 13-HPODE, and 13-HPOTE, U.S. Pat. No. 5,942,661 to Keller claims transgenic crop plants that produce said hydroperoxy fatty acids in amounts sufficient to inhibit the production of fungal mycotoxins.
• said U.S. Patent as well as data by Burow et al.
• null-LOX-1 kernels lack active LOX-1 enzyme, said kernels contain slightly higher levels of 13-HPODE than wild-type plants, but also lower levels of 9-HPODE relative to the tissue of its non-genetically modified parent plant. Relative to wild-type kernels, null-LOX-1 kernels can therefore ward off colonizing Aspergillus, or exhibit reduced mycotoxin levels following contamination with Aspergillus.
• the present invention relates to barley plants with reduced levels of mycotoxins compared to wild-type barley plants.
• null-LOX-1 barley for production of fragrances and green note compounds.
• most research efforts related to the various branches of the LOX pathway in barley have focused on aspects of jasmonic acid generation from 13-HPOTE (Turner et al., 2002), and on disease resistance as described above. Less attention has been paid to barley hydroperoxy fatty acids for alternative, commercial purposes.
• the total absence of active LOX-1 in null-LOX-1 barley kernels is anticipated to enrich 13-HPODE and 13-HPOTE in said kernels.
• null-LOX-1 kernels for the production of green note compounds comprises the use of a novel raw material for said production.
• the novel raw material derived from null-LOX-1 barley kernels of the present invention cannot be considered a standard plant material, since it is derived from kernels that have been selected following a mutagenesis protocol as detailed in Sections 6.4-6.7 of the instant publication.
• null-LOX-1 barley kernels Industrial usage of null-LOX-1 barley kernels is considered outside the scope of the claims recited in the patents described in the previous paragraph, primarily because the novel raw material produced from null-LOX-1 kernels of the instant invention will greatly improve the normal limitations imposed by LOX-1 -catalyzed generation of 9-HPODE and 9-HPOTE - two hydroperoxy fatty acids that cannot function as precursor molecules for the enzymatic generation of the green notes c/s-3-hexenal and c/s-3-hexenol.
• the present invention relates to transgenic barley plants having the null-LOX-1 trait. It is envisioned that future advances in the genetic engineering of plants will lead to generation of barley plants with suppressed synthesis of LOX-1. The concept has been proposed as a means to control off-flavor formation, but results of such an approach are not reported (McElroy and Jacobsen, 1995). The invention described herein may be used in conjunction with such future improvements to generate antisense LOX-1 plants having antisense constructions complementary to at least a portion of the messenger RNA (mRNA) for the LOX-1 sequences can be constructed.
• mRNA messenger RNA
• Antisense nucleotides are constructed to hybridize with the corresponding mRNA, for example, similar to that described for expression of antisense SnRK1 protein kinase sequence in transgenic barley (Zhang et al., 2001). Modifications of the antisense sequences may be made as long as the sequences hybridize to and interfere with expression of the corresponding mRNA. In this manner, antisense constructions having 70%, preferably 80%, more preferably 85% sequence identity to the corresponding antisense sequences may be used. Furthermore, portions of the antisense nucleotides may be used to disrupt the expression of the target gene.
• sequences of at least 50 nucleotides, 100 nucleotides, 200 nucleotides, or greater may be used.
• the applicability of this invention is not limited only to those plants generated by conventional mutagenesis methods.
• targeted gene replacement via homologous recombination is extremely facile in yeast, its efficiency in most multicellular eukaryotes is still limited, and does not yet allow for the generation of such barley plants, as well as the generation of a set of genome-wide gene disruptions (Parinov and Sundaresan, 2000).
• RNA interference RNA interference
• the nucleotide sequences of the present invention may also be used in the sense orientation to suppress the expression of endogenous genes encoding LOX enzymes in plants.
• Methods for suppressing gene expression in plants using nucleotide sequences in the sense orientation are known in the art (see, for example, U.S. Pat. No. 5,283,184 to Jorgensen and Napoli).
• the methods generally involve transforming plants with a DNA construct comprising a promoter that drives expression in a plant operably linked to at least a portion of a nucleotide sequence that corresponds to the transcript of the endogenous gene.
• nucleotide sequence has substantial sequence identity to the sequence of the transcript of the endogenous gene, preferably greater than about 65% sequence identity, more preferably greater than about 85% sequence identity, most preferably greater than about 95% sequence identity. It is notable that various aspects related to heterologous expression of genes encoding LOX enzymes are described and disclosed in U.S. Pat. Application Publication No. 2003/0074693 A1 to Cahoon et al.
• the present invention also rel tes to methods of reducing or preventing the activity of barley LOX-1.
• LOX inhibitors can be selected from the classes of redox and non-redox inhibitors, antioxidants, iron-chelating agents, imidazole-containing compounds , benzopyran derivatives, and the like.
• the invention in one embodiment relates to a method of reducing the activity of barley LOX (preferably LOX-1 ) comprising the steps of (i) providing a barley plant or part thereof or a plant product prepared from barley, (ii) providing a LOX inhibitor (iii) incubating said barley plant or part thereof or plant product prepared from barley with said LOX inhibitor, thereby reducing the activity of barley LOX (preferably LOX-1 ).
• said plant product is malt and said LOX inhibitor is added to said malt during a mashing process.
• Said barley plant or part thereof or a plant product prepared from barley may be null-LOX-1 barley or part thereof or plant product prepared from null-LOX-1 barley.
• other barleys may preferably be used with the methods.
• redox LOX inhibitors may be selected from catecholbutane derivatives, such as any of the ones described inU.S. Pat.
• An antioxidant LOX inhibitor is advantageously selected from among phenols, flavonoids and the like.
• An antioxidant LOX inhibitor may also be selected from gallates, including octyl gallate. It may be confirmed that a compound indeed is a LOX inhibitor by an assay as described in Example 18 herein below.
• octyl gallate is a known inhibitor of soybean iipoxygenase (Ha et al., 2004), and it is of particular interest as it is currently permitted for use as an antioxidant additive in food (Aruoma et al., 1993). This property made it of interest to test purified barley LOX-1 for activity in the presence of the putative inhibitor octyl gallate. Interestingly, the presence of octyl gallate during mashing result in lower levels of T2N.
• An embodiment of the instant invention is therefore to provide an inhibitor of LOX-1 as well as uses thereof, which - following addition to a mash - will confer reduced levels of T2N.
• Mutant grains of the resulting M3 generation were expected to occur at a frequency of 0.9-2.3 per 10,000 grains (Kleinhofs et al., supra). It is notable that M2 grains were not screened, primarily because these contain a relatively high proportion of heterozygous point mutations.
• the assay was based on the LOX-catalyzed generation of linoleic acid hydroperoxides, which - in a haemogolobin-catalyzed reaction - oxidatively couple 3-methyl-2- benzothiazolinone with 3-(dimethylamino)benzoic acid, resulting in the formation of a blue color that can be measured spectrophotometrically.
• one assay series was initiated by the separate homogenization of 96 barley embryo tissues, including the scutellum, into compositions of fine powder.
• the 96-well plate was transferred to a Biomek 2000 Laboratory Automation Workstation (Beckman-Coulter), which was programmed for pipetting according to the LOX assay as described by Anthon and Barrett (supra).
• 96 x 26 ⁇ l embryo extracts were transferred to a standard 96-well microtitre plate (Nunc), followed by addition of 90 ⁇ l of Reagent A [12.5 mM 3-(dimethylamino)benzoic acid, 0.625 mM linoleic acid (prepared as detailed in Example 9)] and 90 ⁇ l of Reagent B (0.25 mM 3-methyl-2-benzothiazolinehydrazone, 0.125 mg/ml haemoglobin); Reagent A was made by first mixing 155 ⁇ l of linoleic acid, corresponding to 134 mg free acid (Sigma, L-1376) and 257 ⁇ l Tween-20, then H 2 O was added to give a volume of 5 ml, followed
• a 5 g 5 was measured in each of the 96 wells of the plate using a Flourostar Galaxy spectrophotometer (BMG Labtechnologies), with the color formation of hydroperoxide products being a measure of the total LOX activity present [activities are accordingly given in A 5 5 units (A 595 U)].
• Neruda (3 lines)]. Grains from each of these mutants were propagated to the M4 generation, harvested, and then re-screened for the trait related to very low LOX activity. Eventually, only one line of cv. Barke, denoted mutant D112, and for one line of cv. Neruda, denoted mutant A618, were shown to exhibit said very low, total LOX activity. Detailed measurements of LOX activities were performed with extracts of mature, quiescent grains, in which the LOX activity was conferred almost exclusively by LOX-1 (Schmitt and van Mechelen, 1997). For embryos of dry, mature M3 grains of mutant D1 12, the total LOX activity - as determined by the colorimetric LOX assay as described above (cf.
• FIG. 2; Table 1) - was 0.407 ⁇ 5.8% A 595 U/embryo, while that for cv. Barke was 1.245 + 7.6% A 5 g 5 U/embryo.
• the LOX activity in embryo extracts of mature, dry grains of generation M3 of mutant A618 was found to be 0.221 ⁇ 2.6% A 595 U/embryo, while 0.721 ⁇ 3.6%> A 595 U/embryo was found in extracts of wild-type cv. Neruda (FIG. 3; Table 1).
• mutant D112 has a wild-type plant growth physiology, but also a normal grain development. Mutant A618 grains of generation M4 and grains of cv.
• mutant A618 were germinated and grown in a greenhouse under light/dark conditions of 20 h/4 h at 12°C and a relative humidity of 65%.
• mutant A618 and cv. Neruda no differences were observed with respect to plant height, number of tillers per plant, the onset of flowering and number of grains per spike.
• the dorsal side grains of mutant A618 differed from the mother cv. Neruda by an abnormal hole-like structure.
• mutant A618 exhibits a wild- type-like plant growth physiology, but an abnormal grain development.
• mutant D112 under field conditions. Mutant D112 and cv. Barke plants were compared in field trials to identify possible differences with respect to plant height, heading date, disease resistance, lodging, ear- breakage, maturation time and yield (see Table 2). The trials were performed according to standard procedures for field trials. Accordingly, equal amounts of kernels of mutant D112 and cv. Barke were sown in 7.88-m 2 plots on 2 locations, each comprising 3 replications. Agronomic data characteristics, with emphasis on the properties described above, were carefully observed throughout the entire growth season. No differences with respect to agronomic traits were observed for neihter mutant D1 12 nor cv. Barke.
• Mutants D112 and A618 are null-LOX-1 plants
• Protein analyses The following analyses were performed to characterize the mutant phenotype of mutants D1 12 and A618.
• Western blot analyses were performed of extracts of embryos removed from quiescent barley grains. One embryo was extracted in 300 ⁇ l ice cold water in a motar, the extracts were transferred to a microcentrifuge tube and centrifuged 10,000 xg. Sample aliquots comprising 10 ⁇ l of crude extracts were separated by sodium dodecyl sulphate- polyacrylamide gel electrophoresis (SDS-PAGE) according to descriptions provided by Laemmli (1970). Separated proteins were thereafter transferred to nitrocellulose membranes by semi-dry blotting as detailed by Towbin et al. (1979).
• the blot was probed with a 1 :500 dilution of the LOX-1 -specific monoclonal antibody 5D2 (Holtman et al., 1996), followed by incubation with goat anti-mouse antibody coupled to alkaline phosphatase, and detected with the alkaline phosphatase substrates nitro blue tetrazolium and 5-bromo-4-chloro-3-indolyl-phosphate as described by Holtman et al. (supra).
• LOX-1 was recognized by the 5D2 antibodies in extracts of cv. Barke embryos, and the protein migrated in SDS-PAGE similarly to that of LOX-1 from cv. Vintage.
• LOX-1 protein could be detected in embryo extracts of cv. Neruda of both generations. However, a very faint LOX-1 protein band was observed in raw mutant A618 and also embryos of the progeny lines (FIG. 8), possibbly because of cross reaction with other LOX enzymes.
• Prestige (denoted genotype NN), the progeny lines were expected to comprise a heterozygous genotype (denoted genotype Nn). It is notable that a low-LOX phenotype, due to its recessive nature, would escape detection in those lines that are heterozygous for the mutation. Self-pollinated progeny plants were expected to yield a population of plants that would segregate in a normal Mendelian pattern, namely in the ratio 1 NN : 2 Nn : 1 nn. The homozygous nn genotype comprising the null-LOX-1 genotype and resulting from the first backcross was expected comprise 50% of the genetic background of cv. Prestige.
• the frequency in the first backcross generation corresponded to 3 lines out of a total of 12 backcrossed lines.
• 9 lines out of a total of 28 backcrossed lines lacked the LOX-1 protein band in the western blot analysis (FIG. 10). Since the recurrent parent background amounts to around 75% in the second backcross progeny, the co-inheritance of the mutated gene for LOX-1 and the corresponding null-LOX-1 phenotype provided confirmation for their genetic linkage. A chi-square test revealed that the observed data could be catagorized as being statistically significant.
• the p value was low ( ⁇ 3.84), a property that showed significance for the first, the second, the third, and the fourth backcross generation.
• the backcrossing program demonstrated that the mutant allele conferring the null-LOX-1 phenotype can be transferred to an alternative genetic background, and that it was inherited in a recessive monofactorial manner following Mendelian segregation.
• Barley of cv. Barke and mutant D112 were propagated in the field for several seasons in order to obtain sufficient grain material for malting and brewing. Analysis of the finished beer for T2N as well as organoleptical analysis demonstrated the improved flavour stability of beer brewed with malt of mutant D112.
• Brewings with malt of mutant D112 and cv. Barke Brewings were performed on a 50-I scale, and involved the following steps: (/) wort preparation; (ii) wort separation; (iii) wort boiling; (iv) fermentation; (v) lagering; (vi) bright beer filtration; and (v) bottling.
• Wort was prepared using malt of mutant D112, or malt of cv. Barke, the latter used as the reference sample. For each brew, a total of 13.5 kg malt was used.
• Mashing-in was at 47°C for 20 min, followed by 18 min of heating in which the temperature was raised from 48°C to 67°C; 30 min pause at 67°C; then heating up to 72°C for 5 min; 15 min pause at 72°C, heating up to 78°C for 6 min; 5 min pause at 78°C.
• the brewing steps of wort filtration and boiling, whirlpool separation, fermentation, lagering and packaging in green glass bottles were according to specifications for standard brewing practice. A total of 33 I beer was bottled.
• Beer was produced using malt of mutant D1 12 and cv. Barke as described above.
• Freshly bottled beer was stored at 5°C and analyzed within 2 months of production.
• the flavor stability of the fresh and stored beers were evaluated following two different types of beer storage conditions.
• the beer was subjected to a forced-aging process at 37°C for a period of 1 to 4 weeks.
• T2N levels of beer samples were determined by gas chromatography with mass spectrometric detection following derivatisation of carbonyls with 0-(2,3,4,5,6- pentafluorobenzyl)-hydroxylamine, essentially as described by Gr ⁇ nqvist et al. (1993).
• a trained beer taste panel evaluated the overall flavor score of the beer.
• the examinations included detection of a cardboard flavor, indicative of free T2N in the beer. It is notable that both types of fresh beer contained similar levels of sulfite, namely 4 ppm and 5 ppm sulfite for the beer derived from malt of mutant D112 and cv. Barke, respectively.
• Forced-aging Bottled beer produced from malt of cv. Barke and bottled beer produced of malt derived from mutant D112 were examined and compared, with resepect to specific data on the development of free T2N during forced-aging as shown in FIG. 12A and Table 5. It is seen that the beers may be distinguished by the pronounced differences in the kinetics of T2N development.
• the taste panel found satisfactory flavor profiles for both types of the fresh and the forced-aged beers (1 week at 37°C). However, the scores for the papery taste were higher for the reference beer than that produced using malt of null-LOX mutant D112 (Table 5), i.e. the reference beer had a more intense taste of the mentioned off-flavor. In general, the taste panel preferred the beer produced from the malt of null-LOX-1 mutant D112 (flavor acceptance score, Table 5). Upon incubation at 20°Gfor 12 months, a panel of 10 beer tasters, who were specialists and trained to taste beer off-flavors compared beers produced from malt of null-LOX-1 mutant D112 and control malt.
• THAs Beer-specific trihydroxyoctadecenoic acids
• null-LOX-1 malt the concentration of 9,12,13-THA was reduced to 20% (i.e. almost 5 fold) compared to the reference beer made from malt of cv. Barke (Table 6), i.e. the isomers 9,12,13- THA and 9,10,13-THA are present in almost equal quantities in beer produced using malt of null-LOX mutant D112. These measurement were carried out using standard HPLC-mass spectrometry analyses.
• EXAMPLE 8 Trihydroxyoctadecenoic acids in beer
• the concentration of THAs in a wide range of commercially available beer samples is shown in Table 7. Close inspection of the result on THAs in beer samples, as shown in Table 7, revealed that the ratio of 9,12,13-THA : 9,10,13-THA always exceeded 3.5. In constrast, in beer produced from D1 12 the ratio of 9,12,13-THA : 9,10,13-THA is 1.3. Hence, beer produced from null-LOX-1 barley comprises a significantly lower ratio, and determination of the 9,12,13-THA :
• 9,10,13-THA ratio provides a tool to determine whether a beer is produced using malt of null-LOX barley mutants, e.g. that of barley mutant D1 12. It is notable that beer produced of malt derived from barley of null-LOX-1 mutant D112 has a significantly lower level of total 9,12,13-THA as compared to beer produced from normal malt.
• Mature wild-type barley grains contain two major LOX activities derived from the enzymes LOX-1 and LOX-2.
• the enzymes catalyze the dioxygenation of linoleic acid into hydroperoxy octadecadienoic acids (HPODEs), with enzyme LOX-1 catalyzing the formation of 9-HPODE and enzyme LOX-2 catalyzing the formation of 13-HPODE.
• HPODEs hydroperoxy octadecadienoic acids
• LOX-1 catalyzing the formation of 9-HPODE
• enzyme LOX-2 catalyzing the formation of 13-HPODE.
• LOX-derived activity is confined to the embryo.
• Barke and similar extracts from barley line G (low-LOX kernels, PCT application PCT/IB01/00207 published as WO 02/053721A1 to Douma et al.), as well as embryo extracts of null-LOX mutant D112 were studied by high pressure liquid chromatography (HPLC) analysis.
• HPLC high pressure liquid chromatography
• Barley embryos The preparations of crude protein extracts from embryos were made by first dissecting the organs from mature barley grains using a scalpel to cut between the scutellum and the endosperm. Each sample, consisting of 4 embryos, was then placed between two pieces of weighing paper, and hammered gently to produce a homogenous flour. This was transferred to a 1.5-ml microcentrifuge tube, 600 ⁇ l of a 200-mM lactic acid buffer, pH 4.5, was added, and the tube was placed on ice for 10 min before further homogenization using a plastic pestle (Kontes). Subsequently, 600 ⁇ l water was added to each tube and the samples were centrifuged for 2 min at 20.000 xg.
• Kontes plastic pestle
• a 100- ⁇ l aliquot of the resulting supernatant was transferred to a 15-ml centrifuge tube [Cellstar (Cat. No.188271) purchased from Greiner Bio-One] to prepare for analysis of the reaction products following LOX action.
• 2 ml of a 100-mM sodium phosphate buffer, pH 6.5, containing 260 ⁇ M linoleic acid [the substrate was prepared by mixing 10 ml of a 100-mM sodium phosphate buffer, pH 6.5, with 100 ⁇ l of a 24-mM linoleic acid stock solution.
• the latter was made by first mixing 155 ⁇ l of linoleic acid (corresponding to 134 mg free acid; L-1376, Sigma) and 257 ⁇ l Tween-20, then adding H 2 O to a volume of 5 ml, followed by addition of 600 ⁇ l 1 M NaOH, and when the solution turned clear, the final volume was adjusted to 20 ml with H 2 O]. After a 15-min incubation on a rotary shaker, 2 ml ethyl acetate was added and the sample content mixed by vigorous shaking for 5 sec in order to extract 9-HPODE and 13-HPODE.
• the sample was then centrifuged for 10 min at 800 xg and 1 ml ethyl acetate was transferred to a 1.5-ml microcentrifuge tube in which the ethyl acetate was evaporated under a stream of nitrogen gas. Subsequently, the HPODEs were resuspended in 300 ⁇ l of methanol, and filtered through a 0.45- ⁇ m membrane (Millex-HN filter, Millipore). Analysis of the HPODE content was performed by HPLC. A total of 15 ⁇ l from each sample was injected into a HPLC apparatus (HP 1100 Series, Hewlett Packard), equipped with a 4.6 x 250 mm Symmetry C18 column (Waters).
• HPLC apparatus HP 1100 Series, Hewlett Packard
• the mobile phase used was a 16:12:12:10:0.5 (v:v:v:v:v) mixture of water : methanol : acetonitrile : tetrahydrofuran : trifluoroacetic acid.
• the flow of the mobile phase was 1 ml per min and the pressure measured in front of the column was 140 bar.
• the separation was performed at 30°C. Detection of hydroperoxides with conjugated double bonds was performed at 234 nm.
• a standard sample comprised a mixture of 9(S)-hydroperoxy-10(£),12(Z)-octadecadienoic acid [(9(S)-HPODE] and 13(S)-hydroperoxy-9(Z),11 (£)-octadecadienoic acid [(13(S)-HPODE], as detailed in FIG. 13A.
• Analyses of the chromatograms revealed that mainly 9-HPODE was formed by LOX enzymes extracted from mature barley embryos of cv. Barke (FIG. 13B), whereas both 9- and 13-HPODE were formed in extracts of mature embryos of the low-LOX line G (FIG. 13C).
• Extracts of mutant D112 embryos formed very low amounts of 9-HPODE, but high amounts of 13-HPODE, thus verifying the absence of LOX-1 activity (FIG. 13D). Accordingly, embryo extracts of mutant D112 formed much less 9-HPODE than those of wild-type barley lines.
• Barley malt Barley malt contains two major LOX activities, derived from LOX-1 and LOX-2. Where LOX-1 catalyzes the formation of 9-HPODE, LOX-2 action generates 13-HPODE.
• HPLC analyses were performed with extracts prepared from malt derived from cv. Barke, barley low-LOX line G and mutant D112. Samples of crude protein extract from malt were made in the following way. One malted barley grain was placed between two pieces of weighing paper, and hammered gently to produce a homogenous flour.
• nucleotide sequence of the gene for LOX-1 in mutant D112 [SEQ ID NO: 2] and in cv. Barke [SEQ ID NO: 1] were obtained and compared in order to determine the molecular basis for the null-LOX-1 phenotype of mutant D112, which has been found to be characterised by the absence of the corresponding LOX-1 enzyme in the grain.
• Genomic barley DNA from mutant D112 and wild-type cv. Barke were isolated from leaf tissues of seedlings using the Plant DNA Isolation Kit (Roche Applied Science), according to the manufacturer's recommendations.
• Barke was amplified by PCR using the primers 5'>GAAAGCGAGGAGAGGAGGCCAAGAACAA ⁇ 3' [SEQ ID NO: 9] and 5'>TTATTCATCCATGGTTGCCGATGGCTTAGA ⁇ 3' [SEQ ID NO: 10].
• Basis for the primer sequences was the genomic sequence of the gene for LOX-1 (van Mechelen et al., 1995; Rouster et al., 1997; a schematic drawing of the genomic sequence spanning the start and stop codons of the region encoding LOX-1 is shown in FIG. 15).
• the PCR reactions consisted of 100 ng genomic DNA in a 20- ⁇ l volume containing 5 pmol of each primer and 3.5 U Expand High Fidelity polymerase (Roche Applied Science).
• the PCR amplifications were carried out in an MJ cycler, using the following cycling parameters: 2 min at 96°C for 1 cycle; 1 min at 95°C, 1 min at 69°C, and 5 min at 72°C for 30 cycles; 10 min at 72°C for 1 cycle.
• the PCR products were separated on 1.0% agarose gels. DNA fragments, corresponding in length to the amplified region, were purified using Qiaex II gel extraction kit (Qiagen), and inserted into the plasmid vector pCR2.1-TOPO (Invitrogen).
• nucleotide sequence of both strands of the coding regions was determined using the dideoxynucleotide chain termination reaction with specific oligonucleotide primers and analysed on a MegaBACE 1000 DNA sequencer (Amersham). Sequence comparisons were performed using the Lasergene sequence analysis software package ver. 5 (DNASTAR). In a direct comparison between the sequence for LOX-1 of wild-type cv. Barke [SEQ ID NO: 1] and mutant D112 [SEQ ID NO: 2], the nucleotide sequence of the mutant revealed one point mutation in the form of a G ⁇ A substitution at position 3574 in exon 7 (FIG. 15; FIG. 16).
• the wild-type sequence for LOX-1 encodes a 862-residue-long protein [SEQ ID NO: 3], with a predicted mass of 96.4 kDa.
• the mutation at position 3574 in the corresponding sequence of mutant D112 causes the introduction of a premature stop codon.
• the stop-codon in the LOX-1 encoding gene of mutant D112 is predicted to result in a C-terminal truncation of 197 amino acids of the correspondig protein, thus encoding a 74.2-kDa protein, the sequence of which is listed in [SEQ ID NO: 4].
• Neruda encodes a 862-residue-long protein [SEQ ID NO: 7], with a predicted mass of 96.4 kDa.
• the mutation at position 2311 in the corresponding sequence of mutant A618 mutates the intron 3 donor site. This causes a splice error in intron 3, theoretically leading to a premature stop codon in the intron 3 after translation of 399 amino acids.
• the inframe stop-codon in the gene for LOX-1 of mutant A618 will result in a truncated translated protein of 44.5 kDa [SEQ ID NO: 8].
• PCT/I B01/00207 published as WO 02/053721 A1 to Douma et al.), cv. Barke, and mutant D112 were grown in a greenhouse during springtime 2002 in Copenhagen, Denmark.
• the ears were tagged at the day of flowering, and spikes were harvested at 20, 4O and 60 days after flowering (DAF).
• the spikes were kept at -80°C until all of the samples could be processed simultaneously.
• a total of 10 embryos per time point were dissected from the developing caryopsis, and RNA was extracted using the FastRNA, Green RNA isolation kit (Qbiogene), using the manufacturer's recommendations. Template for the RT-PCR reactions consisted of 100 ng RNA of the embryos described above.
• RT-PCR reactions contained 50 pmol of each primer and 5 U RT-PCR enzyme mix (Promega).
• the RT-PCR amplifications were carried out in an MJ cycler: 45 min at 48°C for 1 cycle; 1 min at 95°C for 1 cycle; 1 min at 94°C, 1 min at 65°C and 1 min at 72°C for 30 cycles; and finally 10 min at 72°C for 1 cycle.
• a reverse primer 5'>GCCAGCTCCGGCACACTT ⁇ 3' [SEQ ID NO: 12] were used to generate a RT-PCR fragment of 292 bp.
• the RT-PCR products were separated on a 1.0 % agarose gel. DNA fragments, corresponding in length to the amplified region, were purified using the Qiaex II gel extraction kit (Qiagen), and inserted into the plasmid vector pCR2.1-TOPO (Invitrogen). The nucleotide sequence of the plasmid insert was sequenced using an ABI Prism 310 Genetic Analyzer (ABI). DNA sequence comparisons were performed using the Lasergene sequence analysis software package ver. 5 (DNASTAR). The resulting PCR product spanned the region corresponding to nucleotide positions 3283 to 3659 in the genomic clone [SEQ ID NO: 1].
• This region comprised intron 5 with a length of 83 bp, which was absent from the RT-PCR template in a DNA-free RNA preparation (FIG. 17A). Since DNA sequence analysis confirmed that the isolated fragment was an integral part of the gene for LOX-1 and verified the absence of the intron 5 sequence, it could be excluded that false amplification yielded fragments from the barley gene for enzyme LOX-2 (FIG. 17D). Accordingly, the amplified fragment represented the product of an RNA transcript amplification. Comparative RT-PCR analysis of RNA purified from barley embryos 20, 40 and 60 DAF of cv. Vintage and mutant line G revealed that the levels of transcripts for LOX-1 are similar for the two varieties at similar developmental stage.
• the transcript level for LOX-1 is gradually increasing in the time period from 20 DAF to 60 DAF (FIG. 17B). In contrast, however, a marked difference was observed when a similar data set was examined for cv. Barke and mutant D112.
• the RT-PCR experiments revealed that the LOX-1 transcripts in mutant D112 were substantially lower in abundance when compared with those of cv. Barke (FIG. 17C).
• the observations may bee explained by a potential mutation in the promoter region of the gene for LOX-1 in mutant D112.
• Other yet unknown factors may be involved in the transcriptional regulation of the gene for LOX-1 in mutant D112. In this respect, it cannot be exluded that the stop codon in the transcript for LOX-1 of mutant D112 confers nonsense-mediated mRNA decay (Isshiki et al., 2001 ).
• Modem barley breeding strategies comprise often biotechnological technologies to accelerate the process from mutagenesis to commercialization. Therefore, it may be useful to implement an early screening of plant material with respect to detection of single nucleotide polymorphisms in genes of interest. Using this technique with genomic DNA and combined with a high-throghput system, it may be possible to narrow down the number of breeding lines with 50% at the seedling stage.
• CAPS assays Cloning and sequencing of the gene for LOX-1 of mutant D112 progeny lines have shown that the mutation is transmitted to the following generation. This technique is laborious and not useful for practical barley breeding.
• the mutation specific for the low-LOX line G could be identified in breeding material using a cleaved amplified polymorphic sequence assay (CAPS assay), as disclosed in Example 4 of PCT application PCT/I B01/00207 published as WO 02/053721 A1 to Douma et al.
• CAS assay cleaved amplified polymorphic sequence assay
• the nature of the mutation in the gene for LOX-1 of mutant D112 cannot be used to generate an altered restriction map in a 60-bp region comprising the mutation.
• SNP assays An alternative solution to this is to perform an analysis comprising single nucleotide polymorphism (SNP).
• SNP single nucleotide polymorphism
• the SNP is a mutation point with at least two different nucleotide represented at one locus.
• the analysis is based on a combination of two sets of genomic PCR reactions. Both reactions contain a locus- specific primer, and one of the two SNP primers (one for each allele of the sequence). Two sets of PCR reactions are performed per plant line and the result of a PCR reaction is either that the SNP primer binds to sequences of the mutant or the wild-type allele (FIG. 18A).
• the SNP analysis can be based on the identification of mutant lines by evaluating the banding pattern following electrophoresis of PCR products.
• Genomic barley DNA from 17 breeding lines and from the wild-type cv Barke were isolated from leaf tissues of seedlings, using the Plant DNA isolation kit (Roche Applied Science) according to the manufacturer's recommendations.
• the oligonucleotide primers used to amplify the SNP of the gene for wild-type LOX-1 were 5'>CAAGGTGCGGTTGCTGGTGTC ⁇ 3' [SEQ ID NO: 13] and 5'>CTCGCGCGTCTCCTTCCAC ⁇ 3' [SEQ ID NO: 14].
• the primers were 5'>CAAGGTGCGGTTGCTGGTGTC ⁇ 3' [SEQ ID NO: 13] and 5'>CTCGCGCGTCTCCTTCCAT ⁇ 3' [SEQ ID NO: 15]. These primer combinations were used in PCR reactions to amplify DNA fragments of 166 bp comprising parts of the coding regions for LOX-1 of mutant D112 or cv. Barke (FIG. 18A).
• the PCR reactions consisted of 100 ng genomic DNA in a 20- ⁇ l volume containing 25 pmol primer and 2.5 U FastStart Taq DNA polymerase (Roche), used according to the manufacturer's instructions.
• the PCR amplifications were carried out in an MJ cycler: 5 min at 96°C for 1 cycle; 1 min at 95°C, 1 min at 70°C, 1 min at 72°C for 20 cycles; and finally 10 min at 72°C for 1 cycle.
• the PCR products were separated on 1.0% agarose gels. DNA fragments, corresponding in length to the amplified region, were purified using Qiaex II gel extraction kit (Qiagen).
• the PCR products were sequenced directly using the dideoxynucleotide chain termination reaction on an ABI Prism 310 Genetic Analyzer. Sequence comparisons were performed using the Lasergene sequence analysis software package ver. 5 (DNASTAR).
• Detection of mutants in sample mixtures The brewing industry may use mixtures of barley and malt for production of beer, a property that may mask unwanted, chemical characteristics of a specific malt variety.
• a simple confirmation for use of a specific seed material may comprise the amplification of the mutant gene by PCR analysis.
• SNP analysis of mixed malt samples was performed using a sample mixture of mutant D112 and cv. Barke, and a sample mixture of mutant line G (PCT application PCT/IB01/00207 published as WO 02/053721 A1 to Douma et al.), and cv. Barke.
• Six barley samples containing 0, 20, 40, 60, 80 and 100% grains of mutant D112 were analyzed.
• oligonucleotide primers used to amplify a 166-bp SNP of the gene for LOX-1 of mutant D112 were 5'>CAAGGTGCGGTTGCTGGTGTC ⁇ 3' [SEQ ID NO: 13] and 5'>CTCGCGCGTCTCCTTCCAT ⁇ 3' [SEQ ID NO: 15].
• the primers used to amplify a 370-bp SNP of the gene for LOX-1 of mutant line G were 5'>TACGTGCCGCGGGACGAGAAG ⁇ 3' [SEQ ID NO: 16] and 5'>TGATCATGACCGGGTTGACGT ⁇ 3' [SEQ ID NO: 17].
• the PCRs were performed as a multiplex reactions using the four primers simultaneously (FIG. 19A). Each reaction comprised 100 ng genomic DNA in a 20- ⁇ l volume containing 50 pmol of each of the primer and 10 ⁇ l RedTaq polymerase solution (Sigma) according to the instruction provided by the supplier of the enzyme.
• the PCR amplifications were carried out in an MJ cycler: 1 min at 95°C for 1 cycle; 1 min at 94°C, 1 min at 66°C, 30 sec at 72°C for 25 cycles; and finally 10 min at 72°C for 1 cycle.
• the PCR products were separated on 1.0% agarose gels. DNA fragments, corresponding in length to the amplified region, were purified using Qiaex II gel extraction kit (Qiagen), and inserted into the plasmid vector pCR2.1-TOPO (Invitrogen).
• the gene for LOX-1 of mutant D112 was shown to contain a premature stop codon (cf. Example 10). Expression in planta of the gene was therefore expected to result in the synthesis of a truncated version of the corresponding LOX enzyme, containing only the first 665 amino acid residues found in wild-type LOX-1.
• the nucleotide sequence specifying the truncated version of LOX-1 was expressed in E. coli cells to verify that it is enzymatically inactive, and cannot catalyze the formation of HPODEs in cells of barley mutant D112.
• Plasmids for expression of wild-type and mutant LOX-1 in E. coli The entire open reading frame encoding LOX-1 was amplified by using a standard PCR protocol.
• the template was barley cDNA (van Mechelen, 1999), and the primers used were 5'>CATATGCTGCTGGGAGGGCTG ⁇ 3' (SEQ ID NO: 18; the start codon marked in bold letters; the Nde ⁇ site underlined) and 5'>GAATTCTTAGATGGAGATGCTGTTGGG ⁇ 3' (SEQ ID NO: 19; the complementary, wild-type stop codon shown in bold letters; the EcoRI site underlined).
• An amplified DNA fragment of 2,597 bp was obtained and purified.
• the PCR fragment was digested with Nde ⁇ -EcoR ⁇ and ligated to the large ⁇ /otel-EcoRI fragment of vector pET19b (Novagen), yielding the expression plasmid pETLI in which the gene for LOX-1 is cloned downstream, in frame of a sequence for a 10-residue-long His-tail.
• DNA sequencing analyses verified that the plasmid insert contained a correct sequence.
• the next experiment comprised construction of a plasmid for expression of the truncated version of LOX-1. The aim was to change codon no. 666 of the open reading frame for LOX-1 of pETLI to a stop codon, such that protein synthesis in E.
• coli cells would generate a truncated version of LOX-1.
• an expression plasmid was constructed in which all codons downstream of that for no. 665 of LOX-1 in pETLI were removed and replaced by the stop codon TGA. The following protocol was used.
• a 129-bp fragment was amplified from pETLI using PCR in the presence of the primers 5'>CTACCCGTACGCGGCGGACGGGCT ⁇ 3' ([SEQ ID NO: 20]; annealing upstream of the mutation in the gene for LOX-1 of mutant D112; Ss/WI site underlined) and 5'>TCCTGAATTCACGCCTGCACCTCCGTATCGC ⁇ 3' ([SEQ ID NO: 21]; EcoRI site underlined; bold letters indicate the complementary sequence of the introduced stop codon).
• the amplification introduced a stop codon and an EcoRI site to the fragment.
• E. coli cells synthesize recombinant LOX proteins.
• E. coli BL21 cells purchased from Novagen, were seperately transformed with vector pET19b and the expression plasmids pETLI and pETL2 (described above). Bacterial cells harboring the plasmids were inoculated in standard Luria Broth (LB) medium and grown for 2 h at 37°C. Thereafter, 1mM IPTG was added to induce expression of the heterologous genes, and the cultures were grown overnight at 20°C.
• LB Luria Broth
• the cells were harvested by centrifugation for 1 min at 1 ,000 xg, followed by resuspension of the cell pellets in a denaturation solution consisting of a 50-mM Na-phosphate buffer supplemented with 6 M guanidine hydrocloride, 0.3 M NaCI and 10 mM imidazole. Following sonication on ice, the lysed cells were centrifuged for 1 min at 14,000 xg and the supernatant was mixed with Ni-resins (Novagen), followed by a 30-min incubation at 4°C. The Ni-resins were precipitated by centrifugation and washed twice with the denaturation solution described above.
• a denaturation solution consisting of a 50-mM Na-phosphate buffer supplemented with 6 M guanidine hydrocloride, 0.3 M NaCI and 10 mM imidazole. Following sonication on ice, the lysed cells were centrifuged for 1 min at 14,000
• His-tagged proteins were eluted twice from the resins using a 50-mM Na-phosphate buffer supplemented with 0.3 M NaCI and 0.5 M imidazole. Aliquots of fractionated, eluted samples were separated by SDS-PAGE (FIG. 20). Distinct bands of -100 kDa, corresponding to LOX-1 , and -66 kDa, corresponding to the calculated mass of truncated LOX-1 , were obtained from cells carrying pETLI and pETL2, respectively. Cells carrying pET19b yielded no bands in the eluted fractions.
• E. coli BL21 carrying pET19b, pETLI , and pETL2 were inoculated in standard LB medium and grown for 2 h at 37°C. Thereafter, 1mM IPTG was added to induce expression of the heterologous genes, and the cultures were grown overnight at 20°C. The cells were harvested by centrifugation for 1 min at 14,000 xg. Cell lysates were obtained by resuspending the cell pellets in a mixture of BugBuster and Benzonase (Novagen).
• LOX activity was measured in the lysates using a lipoxygenase assay reagent containing 6.25 mM 3-dimethylaminobenzoic acid, 0.3125 mM linoleic acid, 0.1 mM 3-methyl-2- benzothiazolinehydrazone, and 0.05 mg/ml hemoglobin. 180 ⁇ l of the reagent was mixed with 10 ⁇ l of the respective cell lysate and incubated 10 min at room temperature. The amount of indamine produced during the incubation, determined spectrophotometrically as the absorbance at 595 nm, corresponds to the lipoxygenase activity of the cell lysate.
• Plasmid constructs Gene sequences are inserted into the polylinker region of standard plasmid vectors, such as pUC18. The inserts are listed in FIG. 21.
• FIG. 21A the maize ubiquitin-1 promoter (Christensen et al., 1992; Jensen et al., 1996) - including intron 1 of the same gene - directs transcription of the bar gene (White et al., 1990), which encodes the selectable marker phoshinothricin acetyl transferase (PAT).
• PAT selectable marker phoshinothricin acetyl transferase
• FIG. 21 B A construct for silencing the expression of the barley gene for LOX-1 is shown in FIG. 21 C. Expression of this construct in barley cells confers total silencing of said gene by formation of intron-spliced hairpin RNA, and is designed according to the data detailed in Figure 1 a of the publication by Smith et al. (2000). Specifically, the sequence denoted "Intron 1" of the construct in FIG.
• FIG. 21 C is identical to the intron sequence shown in Figure 1a of the publication by Smith et al. (supra).
• the sense and antisense arms of the construct in FIG. 21 C represent opposite directions of the same ⁇ 200-bp-long fragment comprising a segment of the open reading frame encoding barley LOX-1 , said segment of the reading frame located anywhere in the open reading frame for LOX-1.
• the 200-bp-long sequence is selected from the sequence downstream of the stop codon of the barley gene encoding LOX-1.
• Transformation and regeneration of transgenic plants Immature barley embryos from greenhouse-grown donor barley plants of cv. Golden Promise are bombarded with a mixture of plasmids containing the inserts shown in FIG. 21 A,B for co-suppression of the barley gene encoding LOX-1 , and a mixture of plasmids shwon in FIG. 21A,C for silencing of said gene. Transformation, selection of transformed cells, and propagation of transgenic plants is performed as detailed by Wan and Lemaux (1994) and Jensen et al. (supra). The transgenic plants are grown for several generations, or pollinated with a different barley cv., followed by identification of off-spring plants with the desired phenotype.
• transgenic kernels are first analyzed for enzymic activity derived from LOX-1 , as detailed in Example 1 of the instant publication. Transgenic kernels having no or very little LOX-1 activity are subsequently examined in malting and brewing experiments as detailed for null-LOX-1 kernels in Example 5 and Example 6 of the instant publication. In addition, extracts of the transgenic kernels are analyzed to identify those having a negative effects on the growth of Aspergillus fungi, using methods as described in U.S. Patent No. 5,942,661 to Keller.
• the process for production of green note compounds comprises:
• EXAMPLE 18 LOX-1 inhibitors
• 100 ml of AB3 growth medium - supplemented with 100 ⁇ g/ml ampicillin - was prepared using the recommendation by the supplier (Remel), and then inoculated with 5 ml of an overnight culture of E. coli BL21 (DE3)pLysS cells transformed with plasmid pETLI (encoding His-tagged LOX-1 ; cf. Example 15).
• the culture was incubated at 20°C for 30 min, then supplemented with 0.4 mM IPTG to induce expression of the heterologous gene, and incubated at 20°C overnight.
• Cells of the culture were pelleted by a 15-min centrifugation, resuspended in 5 ml BugBuster HT (Novagen), and incubated for 20 min with gentle shaking to hydrolyze nucleic acids. Thereafter, cell debris was removed by centrifugation, the supernatant cleared by filtration through a 0.45- ⁇ m filter, and added to an equal volume of Binding buffer (50 mM Na-phosphate buffer, pH 7.5, supplemented with 0.3 M NaCI, 10 mM imidazole).
• Binding buffer 50 mM Na-phosphate buffer, pH 7.5, supplemented with 0.3 M NaCI, 10 mM imidazole.
• LOX-1 was subsequently used in assays to determine whether selected LOX inhibitors reduce the enzymic activities.
• a stock solution of linoleic acid (prepared as detailed in Example 9), was diluted to 1/10 of its initial concentration, yielding a solution of 2.4 mM linoleic acid. 45- ⁇ l aliquots hereof were supplemented with 5- ⁇ l ethanolic solutions containing of 0, 5, 12, and 24 mM octyl gallate or NDGA (putative LOX-1 inhibitors).
• LOX-1 enzymic activity was determined as the slope of the graph with A 254 plotted against time. The results are summarized in FIG. 22B, showing a pronounced inhibition of LOX-1 at micromolar concentrations of the inhibitors.
• Parallel-running mashings comprised experiments with malt of barley cv. Barke without added octyl gallate, as well as mashings with malt of null-LOX-1 barley mutant D112 in the presence or absence of 0.5 mM octyl gallate.
• Sample aliquots of all of the fours mashings were collected after the 15-min mashing-in phase after the wort boiling phase, followed by determination of T2N levels as described in Example 6. The results are summarized in FIG. 23. A marked decrease in T2N was observed in wort samples of the mashing with malt of barley cv.
• Germination index (scale 1 to 10) 7.3 5.6
• Plasmid Activity 3 pET19b 0.0723 ⁇ 0.0002 pETLI 1.0612 ⁇ 0.004 pETL2 0.0690 ⁇ 0.0002 a The results are given as the mean value of four individual measurements with variation indicated.
• nucleic acid Oligonucleotide primer used for PCR amplification (antisense primer; cf. Example 12, FIG. 18)
• NO: 15 Nucleic acid Oligonucleotide primer used for PCR amplification (antisense primer; cf. Example 12, 15 and FIG. 18, 20)
• ATCC accession number is PTA-5584. Aliquots of the deposited material can be obtained from ATCC by specifying the accession number and by accepting the standard restrictions imposed by ATCC. However, it should be understood that the availability of a deposit does not constitute a license to practice the subject invention in derogation of patent rights granted by government action.
• various publications, patents and patent applications are referred. The disclosures of these publications in their entireties are hereby incorporated by reference into this publication in order to more fully describe the state of the art to which this invention pertains.
• the foregoing description of the invention is exemplary for purposes of illustration and explanation. It should be understood that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are intended to be interpreted to embrace all such modifications.
• Giaever, G. et al. "Functional profiling of the Saccharomyces cerevisiae genome.” Nature 418:387-391 , 2002. Goenczy, P. et al., "Functional genomic analysis of cell division in C. elegans using RNAi of genes on chromosome III.” Nature 408:331 -336, 2000. Graef, G.L. et al. "Fatty acid development in a soybean mutant with high stearic acid.” J. Am. Oil Chem. Soc. 62:773-775, 1985. Griffiths, A. et al., "Fruit-specific lipoxygenase suppression in antisense-transgenic tomatoes.” Postharvest Biol.
• Kitamura et al. "Genetic analysis of a null-allele for lipoxygenase-3 in soybean seeds.” Crop Sci. 23:924-927, 1983. Kleinhofs, A. et al., "Induction and selection of specific gene mutations in Hordeum and Pisum.” Mut. Res. 51 :29-35, 1978. Kolomiets, MN. et al., "Lipoxygenase is involved in the control of potato tuber development.” Plant Cell 13:613-626, 2001. Kuroda et al., "Characterization of factors involved in the production of 2(E)-nonenal during mashing.” Biosci. Biotechnol. Biochem. 67:691-697, 2003.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Genetics & Genomics (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Wood Science & Technology (AREA)
• Zoology (AREA)
• Bioinformatics & Cheminformatics (AREA)
• General Engineering & Computer Science (AREA)
• General Health & Medical Sciences (AREA)
• Biochemistry (AREA)
• Food Science & Technology (AREA)
• Biotechnology (AREA)
• Molecular Biology (AREA)
• Biomedical Technology (AREA)
• Microbiology (AREA)
• Botany (AREA)
• Environmental Sciences (AREA)
• Developmental Biology & Embryology (AREA)
• Biophysics (AREA)
• Plant Pathology (AREA)
• Physics & Mathematics (AREA)
• Cell Biology (AREA)
• Physiology (AREA)
• Medicinal Chemistry (AREA)
• Nutrition Science (AREA)
• Natural Medicines & Medicinal Plants (AREA)
• Breeding Of Plants And Reproduction By Means Of Culturing (AREA)
• Micro-Organisms Or Cultivation Processes Thereof (AREA)
• Non-Alcoholic Beverages (AREA)
• Cereal-Derived Products (AREA)
• Seasonings (AREA)
• Distillation Of Fermentation Liquor, Processing Of Alcohols, Vinegar And Beer (AREA)
• Alcoholic Beverages (AREA)
• Enzymes And Modification Thereof (AREA)

Priority Applications (12)

Applications Claiming Priority (2)

Related Parent Applications (1)

Related Child Applications (2)

Publications (2)

Family

ID=34920665

Family Applications (1)

Country Status (13)

Cited By (11)

Families Citing this family (17)

Family Cites Families (19)

• 2004
  • 2004-03-11 US US10/800,200 patent/US7420105B2/en active Active
• 2005
  • 2005-03-09 CA CA2558815A patent/CA2558815C/en active Active
  • 2005-03-09 EP EP05706820.7A patent/EP1727905B1/en active Active
  • 2005-03-09 BR BRPI0508554-3A patent/BRPI0508554B1/pt active IP Right Grant
  • 2005-03-09 UA UAA200610769A patent/UA89632C2/ru unknown
  • 2005-03-09 EA EA200601669A patent/EA014705B1/ru unknown
  • 2005-03-09 NZ NZ550204A patent/NZ550204A/en unknown
  • 2005-03-09 WO PCT/DK2005/000160 patent/WO2005087934A2/en active Application Filing
  • 2005-03-09 ZA ZA200608444A patent/ZA200608444B/xx unknown
  • 2005-03-09 JP JP2007502192A patent/JP4805249B2/ja active Active
  • 2005-03-09 AU AU2005221763A patent/AU2005221763C1/en active Active
  • 2005-03-09 US US10/598,779 patent/US7838053B2/en active Active
  • 2005-03-09 CN CN200580015328XA patent/CN1981041B/zh active Active
  • 2005-03-09 EP EP10181800A patent/EP2290089A3/en not_active Withdrawn
  • 2005-03-11 AR ARP050100930A patent/AR049008A1/es active IP Right Grant
• 2010
  • 2010-11-22 US US12/951,569 patent/US20110195151A1/en not_active Abandoned
• 2011
  • 2011-04-12 JP JP2011088647A patent/JP2011135900A/ja not_active Withdrawn
• 2012
  • 2012-08-07 AR ARP120102888A patent/AR087480A2/es not_active Application Discontinuation
• 2014
  • 2014-05-16 US US14/279,569 patent/US20150218498A1/en not_active Abandoned
• 2018
  • 2018-09-28 US US16/145,998 patent/US20190078042A1/en not_active Abandoned

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events